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GEOLOGY OF THE THOUSAND 
ISLAND REGIONS 


|f : t .. A THESIS 

Presented to the Faculty of the Graduate School 
of Cornell University for the degree of 

DOCTOR OF PHILOSOPHY 


BY 

HENRY PLATT CUSHING 








[Reprinted from New York State Museum, Bulletin 145.] 






I* 


New York State Education Department 

Science Division, October 4, 1909 

Hon. Andrew S. Draper LL.D. 

1 

Commissioner of Education 

Sir: I have the honor to communicate herewith for publication as 
a bulletin of the State Museum a manuscript entitled Geology of the 
Thousand Islands Region, covering the areas known as the Alexandria 
Bay, Cape Vincent, Clayton, Grindstone and Theresa quadrangles. 
This is a report upon several seasons of field work in the region re¬ 
ferred to, by Prof. H. P. Cushing, Prof. Herman L. Fairchild, Dr 
Rudolf Ruedemann and Prof. C. H. Smyth jr of this staff. 

Very respectfully, 

John M. Clarke 

Director 

State of New York 
Education Department 

commissioner’s room 

Approved for publication this 5 th day of October 1909 



f 













































































Education Department Bulletin 

Published fortnightly by the University of the State of New York 

Entered as second-class matter June 24, 1908, at the Post Office at Albany, N. Y., under 

the act of Congress of July 16, 1894 

No. 485 ALBANY, N. Y. December 15, 1910 


New York State Museum 

John M. Clarice, Director 

Museum Bulletin 145 

GEOLOGY OF THE THOUSAND ISLANDS REGION 

ALEXANDRIA BAY, CAPE VINCENT, CLAYTON, GRIND¬ 
STONE AND THERESA QUADRANGLES 

BY 

H. P. CUSHING, H. L. FAIRCHILD, R. RUEDEMANN & 

C. H. SMYTH JR 

INTRODUCTION 1 

The field work on which the accompanying report is based was 
done during the field seasons of 1906, 1907 and 1908. The dis¬ 
trict was chosen for work chiefly on the recommendation of 
Professor Smyth, and work was begun by the writer with the 
understanding that we were to collaborate in doing it. Unfortu¬ 
nately this plan failed of realization, owing to Mr Smyth’s inability 
to take the field, so that his actual participation in the work was 
limited to a portion of the season of 1908, during which he 
mapped the major portion of Wellesley island. 

Dr Ruedemann assisted in the mapping of the southern part 
of the Theresa quadrangle during two weeks of the season of 
1907 and in 1908, mapped Cape Vincent and the southern half of 
Clayton. The remainder of the areal mapping is the writer’s 
contribution, comprising the Theresa, Alexandria and Grind¬ 
stone sheets (with the exception of Wellesley island) and the 
north half of Clayton. 

Note. The photographs credited to Ami and Ulrich are published by 
permission of the Directors of the Geological Surveys of Canada and of 
the United States. 

1 By H. P. Cushing. 









6 


NEW YORK STATE MUSEUM 


Professor Fairchild spent the season of 1908 and portions of 
two previous seasons in the study of the Pleistocene geology of 
the area, and his reports will be found included in their appro¬ 
priate places. 

During both the seasons of 1907 and 1908 Dr E. O. Ulrich of 
the United States Geological Survey was in the field for a time 
with Dr Ruedemann and myself. In 1908 Dr H. M. Ami of the 
Geological Survey of. Canada was also present and we spent 10 
days together, chiefly in study of the Pamelia, Lowville and Black 
River limestones, with a short excursion to the district around 
Kingston, under Dr Ami’s guidance. Combined work of this sort 
is of the utmost value, and as a result of it the indirect contribu¬ 
tion of both these gentlemen to this report is most important and 
is gratefully acknowledged. 

In a previous year Professor Smyth had reported upon the 
larger part of the district comprised in the Alexandria and Grind¬ 
stone sheets, as well as their eastward extension, doing the work 
as accurately as the imperfect base map at his disposal war¬ 
ranted. It is a pleasure to testify to the importance and ac¬ 
curacy of this report, especially in view of the date at which, 
and the circumstances under which the work was done. 1 2 The 
different rock groups and their relations to one another were 
thoroughly worked out, and the independent mapping here re¬ 
ported upon has done little more than to repeat his work and 
emphasize its correctness. This of itself would justify his ap¬ 
pearance as a collaborator in this report, independently of his 
direct contribution. 

For five weeks of the season of 1908 Dr H. N. Eaton of Chapel 
Hill, N. C., served as voluntary assistant. This generously given 
help is gladly acknowledged, and the report also bears witness to 
the service of his camera. 

LOCATION AND CHARACTER 2 

These five quadrangles constitute the extreme northwestern 
portion of northern New York, bordering the lower end of Lake 
Ontario and the St Lawrence river in the Thousand Islands 
region. The area mapped extends from the meridian of 75 0 45' w. 
longitude to Lake Ontario and from latitude 44 0 to the national 
boundary. It comprises some 560 square miles. 

1 Geology of the Crystalline Rocks near the St Lawrence River. N. Y 
State Geol. 19th An. Rep’t 1899. p.rSs-io.!. 

2 By H. P. Cushing. 



GEOLOGY OF THOUSAND ISLANDS REGION 


7 


The area is one of low altitude and comparatively little relief, 
forming the west end of the plain which borders the entire north 
front of the Adirondack highland, and merges hereabouts into 
the north end of the Black river lowland. To the southward 
the altitude considerably increases and a.bit of the high Trenton 
escarpment which forms the west wall of the larger part of the 
valley of the Black river, appears in the extreme southwest 
corner of the Theresa sheet, reaching an altitude of over 800 
feet, the highest elevation in the mapped district. Altitudes con¬ 
siderably in excess of this appear not far to the southward on the 
\\ atertown sheet. But with this one trifling exception the high¬ 
est elevations in the mapped area but little exceed 600 feet 
(this in the southeast corner of the Theresa sheet) and thence 
drop gently to the north and west to the level of the lake and 
river (246 feet). 

Though the district is thus moderately flat, the local relief is 
considerable, in minor fashion. Ridges and valleys characterize 
the districts underlaid by Precambric rocks. The flat-lying 
Paleozoic rocks form plains which are fronted by steep cliff 
escarpments. In both cases abrupt changes of level of from 50 
to 100 feet are quite common. These features also are most 
pronounced in the eastern part of the area and fade out westward, 
so that but little relief is manifested on the Cape Vincent and 
the larger part of the Clayton sheet. 

With the exception of the St Lawrence, the Black and Indian 
rivers are the only streams of respectable size within the mapped 
area. Most of the streams flow in narrow, steep walled valleys, 
and no deep, broadly opened valleys have been detected. There 
are many features of interest in the minor drainage to which 
attention will be directed later on. The group of lakes of an 
unusual type forms a very prominent feature. Several of these 
lakes may be noted near the eastern edge of the Alexandria sheet 
and there are a few more beyond the map limits. They are not 
a usual feature of this part of the State. Their presence and 
their very localized distribution require explanation. 

Glacial deposits are in small bulk in the district and much bare 
rock appears, with wide areas where the soil is very thin. In 
the limestone districts the streams show a tendency to go under¬ 
ground and bared limestone surfaces show considerable amount 
of rock removal through solution along the joint planes. 

The district is largely one of small farms. Little or no forest 
remains on it, though there is much waste land. The largest 


8 


NEW YORK STATE MUSEUM 


single area of the sort appears in the southeast part of the 
Theresa sheet, on which is found the western portion of the 
“ sand plains,” the great Pleistocene delta of the Black river. 

Interesting historically from having been the scene of exploita¬ 
tion and settlement by French immigrants of high class, during 
the early part of the nineteenth century, the district preserves 
many traces of this immigration, especially in the matter of 
geographic nomenclature. 

SUMMARY OF GEOLOGIC HISTORY 1 

The rocks of the region are readily separable into two great 
groups, the one of older crystalline rocks, and the other ot 
younger Sandstones, limestones and shales which rest upon the 
older group. The rocks of the older group are of Precambric 
age, are among the most ancient rocks of which we anywhere 
have knowledge, and are in most respects identical with the 
crystalline rocks which compose the great central region of 
northern New York, the Adirondack region, and with those of 
the much more extensive area which lies to the northward in 
Canada. These rocks, in the district here reported upon, form 
a narrow connecting link, or isthmus, between the exposures of 
these two areas, which otherwise are completely separated 
from one another by a belt of country of considerable width in 
which the surface rocks belong to the younger group. It is 
only in the immediate region therefore that direct connection 
can be traced between the old rocks of Canada and of New 
York, and this fact gives added interest to the study of these 
rocks here. 

These Precambric rocks furnish us with our most ancient direct 
records of the history of the earth, but like most ancient records 
they are fragmentary and difficult to decipher. Nevertheless they 
plainly indicate that Precambric. time was of enormous duration, 
involving many millions of years. 

Here, as elsewhere in northern New York, these rocks consist 
of but a single series of water-deposited rocks, so far as our 
knowledge goes. 1 his is known as the Grenville series, and 
comprises rocks which, originally deposited as shales, limestones, and 
sandstones, are now greatly changed in character and have become 
white, coarsely crystalline limestones, glassy quartzites, and schists 
and gneisses of many varieties. Curiously we have not as yet, in 

1 By H. P. Cushing. This is a simple statement of the outlines of the 
history of the region as disclosed by the study of the district. The detailed 
evidence upon which these statements are b^sed, will follow later. 



GEOLOGY OF THOUSAND ISLANDS REGION 


9 


New \ ork, been able to discover anywhere any trace of the 
older rocks which formed the floor upon which these water-laid 
sediments were deposited, though plainly, with such an origin, 
they must originally have been laid down on some such floor of 
older rocks. It follows therefore that we do not know the base 
of this Grenville series. Neither do we know its summit, since 
that has apparently been everywhere removed by erosion. 
Hence we can not know its thickness, though we do know that 
it is a very thick rock series, several thousands of feet at least. 

Since the deposition of this formation it has undergone many 
changes. The rocks have been greatly compressed and intri¬ 
cately folded and plicated. They have been invaded from be¬ 
neath by huge masses of igneous rocks, which have broken up the 
once continuous Grenville formation into separate and discon¬ 
nected belts and patches, have probably engulfed and. digested 
large amounts of it, and are likely responsible for the utter dis¬ 
appearance of the old floor on which the formation originally 
rested. As a result of this mishandling the rocks have been pro¬ 
foundly changed in character. They have been entirely re¬ 
crystallized, with complete destruction of the textures which, as 
sediments, they originally possessed, and with the production of 
a foliation cleavage, or schistosity, due to a banded arrangement 
of the minerals formed by the recrystallization. In addition a 
quantity of contact rocks has been produced in the vicinity of, 
and by the action of, the igneous rocks, which interact with the 
others to produce rocks quite different from either, and with 
opportunities for manifold variation, with variation in the 
character of either or both sets of the original rocks. In this 
manner many rock types have arisen, often of puzzling nature. 

The changes which have been produced in these Grenville rocks 
are of such nature as to lead to the confident belief that they took 
place at some considerable depth below the surface, or in other 
words that a considerable thickness of other rocks then overlay 
them, a rock thickness which subsequently disappeared because of 
surface wear continued through long ages. 

Igneous intrusions 

As has been implied the Grenville sediments are the most ancient 
rocks of which we have definite knowledge in northern New York. 
Subsequent to their formation they were repeatedly invaded from 
beneath by igneous rocks in molten condition. In the immediate 
district the bulk of this igneous rock consisted of granite, and 


IO 


NEW YORK STATE MUSEUM 


the more basic rocks which appear in large quantity further east 
are but sparingly present. But granitic intrusion took place on a 
large scale at least twice, probably three times, and possibly sev¬ 
eral times. This it was which was so effective in breaking up, al¬ 
tering and destroying wholesale the Grenville sediments and their 
floor. 

Laurentian granite gneiss. The oldest of these igneous rocks 
is a granite which has, since its intrusion, been sufficiently sub¬ 
jected to compression to have become pretty thoroughly crushed, 
or granulated, with the development of a rude foliated, or gneis- 
soid, structure. It is a reddish to gray granite gneiss which con¬ 
tains nearly everywhere inclusions of the Grenville rocks in vary¬ 
ing abundance, but always most abundant near the contacts with 
the Grenville, into which it always sends a multitude of dikes. 
The inclusions are usually of amphibolite and all stages of their 
assimilation by the granite are found, giving rise to a group of 
intermediate rocks which seem unquestionably to have been de¬ 
rived from the digestion of the one rock by the other. It is pos¬ 
sible that some of these amphibolite inclusions may actually repre¬ 
sent fragments of the old Grenville floor, and furnish the sole re¬ 
maining traces of that floor, but as yet this is mere conjecture. 
This granite gneiss occurs in both large and small masses, so called 
bathyliths and stocks, which invaded the Grenville rocks from be¬ 
neath at an exceedingly early period. 1 In addition to forming a 
large portion of the present surface occupied by the Precambric 
rocks it likely also underlies the Grenville rocks over the entire 
district, except where they have been cut away by succeeding 
igneous rocks. Since the rock solidified it has been subjected to 
compression, together with the Grenville rocks, giving to each a 
foliation parallel to that of the other, and elongating the bathyliths 
in a northeast-southwest direction with corresponding shortening 
at right angles to this, the shortening being of course in the di¬ 
rection of the pressure and the elongation at right angles to it. 

Alexandria syenite. On the Alexandria quadrangle, some 3 
miles a little west of north of Redwood, is a mass of rather coarse 
grained igneous rock which shows little sign of crushing and is un¬ 
questionably younger than the Laurentian granite gneiss. In as¬ 
sociation with it is a much greater amount of a coarse, but crushed, 
porphyritic igneous rock, now converted into an “ augen ” gneiss. 

1 Bathylith is a terrn applied to large masses of igneous rock, which masses 
are believed to continue to great depths with generally increasing size 
downward. A stock is a smaller mass of the- sort. 



GEOLOGY OF THOUSAND ISLANDS REGION 


II 


What relation the two bear to one another could not be definitely 
ascertained. Either the augen gneiss is a crushed border phase of 
the other, that representing an uncrushed core, or else it is a 
sepaiate and older rock. It is a fairly basic rock, varying much in 
this lespect, seems at times to owe its character to partial as¬ 
similation of amphibolite, and so far as seen, its exposed contacts 
are all with Grenville rocks, which it cuts. If the two intrusives 
belong together the mass reaches considerable size and is to be 
classed as a small bathylith. If the augen gneiss is distinct from 
the other the latter is only a stock. 

In case the augen .gneiss is distinct the question naturally arises 
whether it may not be merely a porphyritic phase of the Lauren- 
tian granite gneiss. A decisive answer to this question can not be 
given owing to lack of contacts between the two classes of rock. 
But such evidence as there is seems decidedly against such a cor¬ 
relation. The rock is a more basic one than the general run of the 
granite gneiss, and is not so severely crushed, or granulated. The 
weight of the evidence is decidedly in favor of the view that it 
is a gneissoid, border phase of the syenite. 

Syenite southwest of Theresa. Up the creek valley above 
Theresa are exposures aggregating about a square mile in extent of 
a gray to gray green rock which is a syenite. It may have con¬ 
siderably greater extent underneath the sandstone which adjoins 
it on each side. It is by no means so mashed as the granite gneiss 
and seems clearly a younger rock, but since it is not found in as¬ 
sociation with any of the other younger igneous rocks its age rela¬ 
tions to them are not ascertainable. 

There is a single outcrop of a coarse, unmashed eruptive which 
is to be classed as a gabbro, close to the upper bridge at Theresa 
on the west bank of the river. It may have considerable extent 
under the adjacent sandstone but with the most generous possible 
allowance for such extension the mass would still have to be rated 
as a stock of no great size. 

Picton granite. 1 The most extensive and important of these 
younger Precambric intrusives is the coarse red granite which out¬ 
crops widely on Grindstone, Wellesley and some of the smaller 

1 The most considerable outcrops of this rock within the State are on 
Grindstone island, but the name of Grindstone granite would perhaps be 
misleading, and Grindstone Island granite is too long a name. The smaller 
Picton island is however the seat of the chief quarries at the present time 
and the name would be wholly appropriate except for the fact that the 
island appears on the maps as Robbins island. It is universally, called 
Picton island by residents, many of whom have no knowledge of any such 
name as Robbins island. 



12 


NEW YORK STATE MUSEUM 


islands, and to a small extent on the mainland, and which is named 
from Picton (Robbins) island, where the most extensive quarries 
occur. This rock shows little or no signs of the crushing which 
has affected the other Precambric intrusives in greater or less de¬ 
gree, though it becomes fine grained in certain situations, chiefly 
marginal, and notably so in many of the dikes which it sends out 
into the adjoining rocks. 

The rock holds a multitude of inclusions, of Grenville quartzites 
and schists, of Laurentian granite gneiss, and of the augen 
gneiss associated with the Alexandria syenite. Over much of 
Wellesley island the abundant inclusions are. but little disturbed, 
in other words their dips and strikes are concordant and in accord 
with those of the neighboring Grenville rocks, and with these un¬ 
changed dips and strikes the inclusions occur in linear belts, now 
of quartzite, now of schists and again of granite gneiss, so that 
the original distribution of these rocks can be mapped as con¬ 
fidently as though the granite invasion had never been. This in¬ 
dicates that here we are near the very roof of the granite bathy- 
lith, where cooling had rendered it so stiff and pasty as to be no 
longer able to pluck away and engulf blocks from its roof, the 
present inclusions being such as had been last broken away but 
were unable to founder and retained their original orientation. 

The utter lack of signs of crushing in the rock leads to the rather 
confident belief that it is the youngest of all these early Precam¬ 
bric intrusives, though there is some question as to whether it is 
actually younger than the syenite and the gabbro about Theresa, 
and with no possibility of definitely settling the matter. 

The bathylith is also of large size, extending out of New York 
into Canada among the islands and on the mainland. The granite 
which outcrops about Kingston seems surely identical, and is dis¬ 
tant 17 miles from the nearest outcrops of the rock on the west 
end of Grindstone island. 

The molten mass of the granite was also richly charged with 
mineralizing fluids and hence exhibits prominent contact effects on 
the adjacent rocks, much more prominent than those shown by any 
of the other intrusives of the immediate region. 

When compared with the Precambric rocks of the general Adiron¬ 
dack region (the rocks hereabouts comprising the extreme western 
edge of the Precambric of northern New York) the most obvious 
difference to be noted is the comparative scarcity of igneous rocks 
belonging to the syenites and gabbros in this western area. 

It seems also to be the case that metamorphism is not so extreme 


GEOLOGY OP THOUSAND ISLANDS REGION 1 3 

here as farther east, in fact there seems to be a slow but progres¬ 
sive increase in severity of metamorphism in passing east. The 
differences in this respect are not so prominent in the Grenville 
and Laurentian rocks as in the later igneous rocks, but character¬ 
ize all. Even here, however, the character of the metamorphism in¬ 
dicates a considerable depth for the rocks concerned during the 
time when it took place. But it also suggests a less depth of over- 
lying material than is possessed by the region farther east. 

This overlying material has since been removed by slow surface 
erosion. Greater thickness has been removed on the east than on 
the west apparently, the differences in metamorphism being thus 
most readily explained. Further, this removal by erosion took place 
wholly in Precambric time indicating that the region was a land 
area for a long period. Precambric time however was very long, 
the Grenville sediments were deposited early in it, the district sub¬ 
sequently rose above sea level and remained as land during the 
long ages of the middle and late Precambric. The large amount 
of rock thickness removed not only argues for a long erosion in¬ 
terval but likely indicates renewal of uplift on one or more oc¬ 
casions, since it is not probable that the region ever attained an 
altitude as great as that represented by the thickness of rock re¬ 
moved. 

Late in Precambric time, and toward the close of this long, 
erosion period, came renewed igneous activity, an upward move¬ 
ment of heavy, black, basic lava taking place. Not improbably 
some of this material reached the land surface of the time and 
spread out as lava flows. If so subsequent wear has removed 
every trace of their presence, cutting away the surface sufficiently 
so that the only sign of this igneous activity which remains on 
the surface of today is the trap dikes, the lava-filled channels of 
ascent of the molten rock. The trap is absolutely unmetamorphosed 
and gives every indication of having solidified at quite shallow 
depth. Hence the conclusion is forced that the eruption occurred 
toward the close of the long Precambric erosion period previously 
described, and since only a comparatively slight amount of wear 
followed, that these dikes are of very late Precambric age; in fact 
it is by no means impossible that they may be as young as the 
early Cambric. 

If we could follow these dikes down into the earth beneath the 
surface of today, no doubt we should find that they lead upward 
from underground masses of trap of considerable size, quite analo¬ 
gous to the bathyliths of the earlier granites. 


14 


NEW YORK STATE MUSEUM 


Close of the long period of erosion 

Eventually this long period of surface wear on a land area drew 
to a close, and for a time the history of the region became of very 
different nature, in other words instead of loss of surface material 
it began to gain it in the shape of deposits on the old, worn land 
surface. These deposits blanketed and preserved the old erosion 
surface, and since the wear of today has come down to that precise 
horizon over parts of the district, and the overlying deposits are 
being peeled away from it, it is returning to daylight with precisely 
the characters it possessed when it was buried and preserved ages 
ago. Seldom does a district reveal so abundant and clear evidence 
of the nature of an old fossil land surface. It is clear from its 
study that long wear had reduced it to a surface of comparatively 
slight relief, showing that no considerable elevation of the region 
occurred during the latter portion of the long erosion interval. 
Nevertheless it is very far from being a plane surface, but is of 
considerable minor relief, of low ridges and. shallow valleys, or of 
low knobs and basins, the depressions eaten out on the weaker rocks, 
chiefly the Grenville limestones and some of the schists, while the 
more elevated ridges and knobs are due to the resisting qualities of 
the Grenville quartzites and of many of the igneous rocks. The 
knob structure is practically confined to the igneous rock areas, 
chiefly in the Laurentian gneiss. 

While the region therefore is quite rugged in a mild fashion, the 
extreme differences in altitude are but slight. One hundred feet is 
about the measure of difference. Seldom does the difference in level 
between valley bottom and ridge crest reach that figure, and rarely 
does it exceed it. This is a small difference, considering the wide 
variation in resisting power to wear which the various rocks present 
and is indicative of a long period of wear under comparatively stable 
conditions of level. 


Paleozoic sediments 

Potsdam sandstone. A change in conditions followed and de¬ 
position of sand commenced upon this old land surface. It natur¬ 
ally began on the valley bottoms and encroached on the ridges only 
as the valleys filled. The old limestone surfaces were pitted by 
small depressions, and were somewhat intersected with widened 
joint cracks also, and in these the first materials collected, some¬ 
times full of coarse fragments of resistant thin quartzite bands or 


GEOLOGY OF THOUSAND ISLANDS REGION 


15 


granite dikes such as are found nearly everywhere in the Grenville 
limestones, sometimes containing only sand. There is comparatively 
little basal conglomerate in the district back from the river, but 
there, both on the mainland of the Alexandria quadrangle and on 
Wellesley and Grindstone islands is an exceedingly coarse conglom¬ 
erate, from 10 to 20 feet thick, full of coarse cobbles derived from 
the ponderous and resistant Grenville quartzite of the vicinity. 

Except for these conglomerates the formation is everywhere a 
sandstone and mostly pretty thoroughly cemented, the cement being 
chiefly of silica. Its colors are red, brown, yellow, white, and rarely 
black. Its thickness over the immediate district will scarcely exceed 
100 feet, and it thins out toward the west and south. The deposits 
of sand began forming first in the Champlain region and gradually 
worked their way westward, being deposited in a shallow trough or 
basin whose axis roughly coincided with the modern St Lawrence 
axis, so that hereabouts we find simply the thinned western edge of 
the formation. As its thickness here is substantially equal to the 
difference in altitude between the ridge crests and valley bottoms 
of the old erosion surface upon which it was deposited, it follows 
that it varies rapidly in thickness from place to place and was but 
scantily deposited upon the elevations, some of which it utterly 
failed to overtop. 

It is not known whether or not the formation in its entirety is a 
marine formation. The sparse fossils indicate such origin for the 
upper beds with comparative certainty, but many things about the 
remainder of the formation suggest a land surface and an arid cli¬ 
mate as the conditions under which the accumulation took place. 

Theresa dolomite. A change in conditions ensued and de¬ 
posit of dolomite began. Some sand was still supplied from the 
neighboring land however, as the dolomite is everywhere sandy, 
and at first the supply was from time to time in excess, so that layers 
of coarse weak sandstone alternate with those of dolomite. Hence 
there is a gradation from one rock to the other instead of a sharp 
boundary between the two. The greatest thickness of the 
formation within the area mapped does not exceed 35 feet, 
though its original thickness may have been somewhat greater. 
The thickness increases eastward and diminishes to the west and 
south as was the case with the underlying sandstone. The 
waters were more fitted for the existence of life and the fossils 
are more abundant than in the sandstone, but unfortunately 
conditions for their preservation have not been favorable. 


16 


NEW YORK STATE MUSEUM 


The Theresa formation followed close after the Potsdam and 
they were laid down in a trough or bay along the present St 
Lawrence line which was landlocked on the north, south and 
west. The depression of this trough originated to the eastward, 
where the deposits are thickest, and deposits did not commence 
in the immediate region until late in Potsdam time. The ex¬ 
treme western extremity of the bay can not have lain many miles 
west of the immediate region at the time of its greatest expan¬ 
sion. Then it commenced to contract and slowly work back east¬ 
ward. 1 

Uplift following the Theresa. This tendency to contraction 
of the trough, caused by slow uplift of the land, seems to have 
continued until the bottoms of both the St Lawrence and the 
Champlain troughs had been raised above sea level, so that all 
the northern portion of the State was above that level. After a 
time renewed depression followed, apparently commencing simul¬ 
taneously on the west, south and east sides of the Adirondacks, and 
the Tribes Hill phase of the Beekmantown formation was laid 
down. This was followed by uplift which began at the west and 
worked eastward, bringing the west and south sides of the district 
above sea level, while subsidence still continued in the Champlain 
valley, in which a large thickness of later Beekmantown rocks 
was deposited. This Tribes Plill subsidence came in on our dis- 
trict here from the south and its deposits constitute the upper 
portion of what is mapped as the Theresa formation. Until the 
Beekmantown formation along the St Lawrence valley has received 
further study we can not say whether the Tribes Hill limestone 
extends -east of the Frontenac axis or not. Our present view is 
that it did not, and that the Beekmantown of the St Lawrence 
valley represents the higher portion of the formation, deposited 
in a trough which extended westward up the valley from the 
Champlain basin. This depression did not carry the immediate 
region below sea level. The district tilted to the southwest and 
received a thin edge of Tribes Hill deposition, then rose and was 
tilted back to the eastward, though not sufficiently to allow the 
later Beekmantown sea of the district to the east to quite reach it. 

1 Since the field work was completed and this report written, work else¬ 
where in New York has shown that probably the Theresa formation, as 
here mapped and described, as in reality composed of two probably 
unconformable formations, of quite different ages, and that the name 
should be restricted to the lowermost of these, the upper being of lower 
Beekmantown age, and equivalent to what we are calling the Tribes Hill 
formation in the Mohawk valley. The matter is discussed in more detail on 
a later page. 



GEOLOGY OF THOUSAND ISLANDS REGION 


1 7 


In the Champlain valley the Beekmantown rocks are overlaid 
by the Chazy limestones. There is evidence there of a break 
between the two formations and the Chazy has a basal sandstone. 
The Champlain Chazy trough also had a westerly bay but it never 
extended as far west as the district under discussion. During the 
long time interval therefore during which Beekmantown and early 
Chazy sedimentation was transpiring in the subsiding Champlain 
trough, the district here was above sea level and experiencing wear 
rather than receiving deposit. Considering the length of the interval 
the amount of erosion which it suffered was but slight, arguing for 
low altitude and gentle slopes for the land. Broad, shallow valleys 
were cut in the surface of the Theresa limestone but the depth of 
cutting seems never to reach the base of the formation. 

Pamelia (Stones River) limestone. The Chazy basin of the 
Champlain, St Lawrence and Ottawa valleys was landlocked to 
the south and west during lower and middle Chazy time. Dur¬ 
ing this time interval, however, other and larger basins of sub¬ 
sidence and deposit existed to the south and west but completely 
separated from the Chazy basin. Both the rocks and the con¬ 
tained fossils therefore differ from the Chazy and the formation 
is known as the Stones River. Notwithstanding difference of 
name the two formations represent substantially the same time 
interval. 

As Chazy time passed on, the large Stones river basin to the 
southward encroached northwardly and toward the latter part of 
the interval had become sufficiently extended to submerge the 
immediate district. The slow warping of the land which brought 
about this subsidence gave the district a wholly different direc¬ 
tion of slope. In Potsdam and Theresa times it had sloped to 
the northeast and formed part of the extreme westerly end of the 
subsiding trough. It now came to slope to the southwest, was in¬ 
vaded by the sea from that direction, and to the northeast lay a 
land area which separated it from the Chazy basin beyond. 
Though the district was covered by the waters of both marine 
invasions it was near the shore line in each case and received 
only comparatively thin, marginal deposits, representing only a 
small fraction of the entire thickness of the formations con¬ 
cerned. Hence in a broad way it is true that what had been the 
western shore of the earlier sea became now the eastern shore 
of this later western sea, or that the general district formed an 
axis or pivot from which the land tipped now in one direction 


i8 


NEW YORK STATE MUSEUM 


and now in the other, remaining throughout an area of small 
subsidence. 

The deposits laid down in this depression are of upper Stones 
River age and the name of Pamelia limestone is proposed for 
this New York phase of the formation. Locally it is known as 
the “ blue limestone ” though the local name commonly includes 
the overlying Lowville limestone as well. A thin, basal sand¬ 
stone appears, after which follow alternating black, blue and 
gray limestone beds, then the black limestone disappears and 
white, earthy limestone alternates with the others. During the 
deposit of this upper portion the waters seem to have become 
shut off from the open sea, by the development of some shoal or 
reef as a barrier, and in the lagoon thus formed water lime was 
deposited, the waters often evaporating sufficiently to expose 
wide mud flats which dried and cracked under the sun’s influence. 
The marine fauna found these conditions uncongenial and disap¬ 
peared, though returning from time to time for a brief space with 
fresh influx of water from the sea outside. Deposition became 
intermittent and eventually ceased and some slight wear oc¬ 
curred locally. 

Lowville, Watertown and Trenton limestones. Subsidence 
then recommenced, and upon this slightly worn Pamelia surface 
the dove-colored limestones of the Lowville formation were laid 
down. The Lowville submergence was somewhat more exten¬ 
sive than the Pamelia, since the former appears in the Mohawk 
valley while the latter does not. And though both formations 
occur along the Black river valley it seems probable that the 
Lowville sea encroached more widely upon the borders of the land 
which lay to the eastward. 

The Lowville is a quite pure limestone for the most part, and 
carries a much more abundant and varied marine fauna than do 
any of the older rocks. Above it lies a more massive, cherty lime¬ 
stone, separated from the main mass of the Lowville by an un¬ 
conformity, which we are calling the Leray limestone, and classing 
as an upper member of the Lowville. Above this, also with an 
unconformity between, comes a similar massive limestone, without 
chert, which we are proposing to call the Watertown limestone. 
The Watertown and Leray limestones taken together are known in 
the region as the Black River limestone, the Leray being locally 
more like the Watertown than like the Lowville in character. Be¬ 
cause of this, and because of their small thickness (about io feet 
each), we have felt constrained to map them together. They carry 


GEOLOGY OF THOUSAND ISLANDS REGION 


19 


an abundant marine fauna, the large cephalopods being especially 
conspicuous. 

1 lie Watertown limestone is unconformably. overlain by the thin 
bedded limestones of the J renton. The time interval between the 
Lowville and the Trenton was a considerable one, but the surface 
exposures of these rocks in New York are so near the old shore 
lines of the time, that the deposits exposed represent the interval 
very imperfectly. The shore line was one of many and frequent 
local oscillations, and the rocks which have, of late years, been 
classified as Black River limestone, represent very different parts 
of this general interval. 

The Trenton limestone is abundantly fossiliferous and has a thick¬ 
ness of 400 feet or more in the immediate region, exceeding the 
combined thickness of the Potsdam, Theresa, Pamelia, Lowville and 
Black River together. Found on all sides of the Adirondacks, and 
with large thickness everywhere, the Mohawk valley excepted, large 
subsidence is shown, with probable great encroachment of the » 
waters upon the Adirondack island, much diminishing its size. 

As Trenton time drew to a close fine muds commenced to appear 
in the waters, brought in by currents from the northeast, and in 
slowly increasing amount. Hence the limestones become impure 
and grade upward into black shales' at first strongly calcareous, 
later on lacking lime. This change came on the region from the 
eastward, hence shales were forming there while limestone was 
still being deposited on the west. But the change to mud deposit 
spread slowly over the whole region and the Trenton is found 
everywhere to be overlaid by the black LTtica shales. This Utica 
submergence seems to have been the most extensive in the State’s 
geologic past, and it is quite possible that the entire Adirondack 
island was submerged. If so it seems to have been the last time 
that such was the case, as it was the first. 

Above the LTica lie the lighter colored shales and shaly sand¬ 
stones of the Lorraine formation, the combined thickness of the two 
shale series being several hundred feet. While neither formation 
is found within the limits of the area mapped, in which the lower 
Trenton is the youngest rock found, yet they outcrop in great thick¬ 
ness on the Watertown quadrangle and reach to within 6 miles of 
the south margin of the Theresa sheet, and it seems quite certain 
that they were originally deposited over part, and likely all, of the 
district mapped, and are now absent from it because of subsequent 
erosion. It is even probable that the Oswego and Medina sand¬ 
stones, thick sand formations which, overlie the Lorraine shales, 


20 


NEW YORK STATE MUSEUM 


and whose present northern margin of outcrop is distant but 15 
miles from the map limits, may also have been somewhat deposited 
within it. Certainly the sandstone extended orginally farther 
north than now, but just how far no one can say. 

The deposit of these sands indicates a shallowing of the waters 
over the region, following which it was uplifted above sea level. 
Thenceforth in the main, throughout the millions of years which 
have since elapsed, the district has remained a land area. It is 
quite possible that the succeeding Siluric and Devonic seas, whose 
waters covered central and western New York, may have washed 
over this district, and laid down thin deposits. But if so, every 
trace of such deposits hereabouts has disappeared through erosion, 
so that no certainty can be arrived at in the matter. 

As a result of the various oscillations of level which the region 
has undergone the rocks described have been changed from their 
original nearly horizontal position, into a series of low folds. This 
folding seems to have commenced early and to have been continued 
on various occasions, since there is some evidence that the Pots¬ 
dam and Theresa formations were somewhat folded before Pa- 
melia deposition began. Subsequently more folding took place, in¬ 
volving the entire series, and though the folding is gentle its topo¬ 
graphic expression is plain. 

The principal folds have axes which trend northeast-southwest, 
but there is also present another set with northwest-southwest trend, 
or at right angles to the first set, whose arches and troughs are 
thus folded up and down, producing gently elevated domes and de¬ 
pressed basins, the former where the arches of the two sets cross, 
and the latter at trough intersections. Many of the outliers shown 
on the accompanying geologic maps owe their existence and pres¬ 
ervation to this folding. 

Subsequent history of the region 

But little that is definite can be said of the history of the district 
during its long existence as a land area following the deposition 
of the rocks previously described. It seems quite certain that the 
amount of rock worn away from the surface during this time is 
slight, considering the length of the time interval, and that there¬ 
fore the land has seldom had any considerable altitude. Where 
the entire thickness of overlying rocks has been worn away and 
the Precambric exposed at the surface, as is the case on parts of 
the Theresa and Alexandria sheets, it seems quite certain that not 


GEOLOGY OF THOUSAND ISLANDS REGION 


21 


over 3000 feet of rock thickness has been removed, and likely con¬ 
siderably less. Since the overlying rock has been worn away down 
to the Precambric over only a small portion of the whole district, 
it follows that in the remainder the erosion has been less than the 
above amount by the remaining thickness of such overlying rock. 
The character of the district to the south of the map limits however 
indicates an uplift of the land of comparative recency to the amount 
of several hundreds of feet, and the present-day stream valleys 
of the region have been worn down below this old level in this 
comparatively recent period. This relatively considerable recent 
elevation and erosion makes still more emphatic the necessity for 
assuming slight elevation of the region during the much longer in¬ 
terval which preceded it. As compared with much of the district 
surrounding it this area has been one of but slight changes of level 
during its past history. While in their early history these surround¬ 
ing districts were submerged and subsiding, allowing thick accumu¬ 
lations of deposits, this area subsided less and received but scanty 
deposit. Only during middle and late Lower Siluric time, during 
Lowville, Trenton, LTica and Lorraine deposition, was it a dis¬ 
trict of considerable subsidence and deposit. In its subsequent 
history as a land area it seems to have been one of but small 
uplift as compared with much of the adjacent region. 

As has been stated, in the comparatively recent past the district 
experienced uplift to the amount of several hundred feet. Prior 
to this it had been worn down to a surface of comparatively slight 
relief. The uplift gave the streams power to deepen their valleys 
by an equivalent amount, and the processes of wear which have 
given the present relief to the region were set in motion. Then, 
as now, the Black river was the chief stream of the neighborhood, 
and perhaps turned west into the Ontario lowland as it now does; 
but the lake was not in existence then, nor was the drainage of the 
lowland to the eastward, but the Black river flowed through it in a 
westerly direction, receiving many tributaries from the north and 
the south. There were also easterly flowing waters in the district, 
however, the beginnings of streams which drained down the St 
Lawrence valley. But the St Lawrence of the time had its sources 
in the immediate region, and contained no waters coming from 
farther west, the divide between the easterly and westerly flowing 
waters being here, crossing the present St Lawrence in the Thou¬ 
sand Island region on the hard rock barrier which the Precam¬ 
bric rocks furnish. On the New York side the divide can be traced 
across the Clayton, Alexandria and Theresa quadrangles in a south- 


22 


NEW YORK STATE MUSEUM 


easterly direction, with sharply cut ravines heading against it on 
both sides, marking the extreme heads of the small streams which 
flowed on the one hand northeast to the St Lawrence, and on the 
other hand southwest to the Ontario drainage. On the Clayton 
quadrangle the French creek valley belongs to the former, and 
the Chaumont river valley to the latter category; on the Alexandria 
most of the country was on the St Lawrence side of the divide, 
the valleys of Crooked creek, Cranberry creek, Butterfield lake- 
Black creek, and the valleys now occupied by the other lakes be¬ 
longing there, while Mullet creek valley drained the other way; on 
the Theresa the valley into which the Indian river breaks at Theresa 
village seems to belong to the easterly drainage, while the remain¬ 
der of the valleys on the quadrangle carried water to the westward 
drainage. 

The valleys excepted, the prominent topographic feature of the 
region is the rock cliffs, usually low, which mark the edges of out¬ 
crop of the various formations, and which owe most of their pres¬ 
ent relief to the wear which followed the considerable uplift. In 
general, each rock formation of the region is somewhat less resistant 
to wear than the formation beneath and somewhat more so than 
the formation above. Hence the overlying formation tends to be 
slowly stripped away from that beneath, which yields more slowly 
and, because of the nearly horizontal attitude of the rocks, remains 
as a comparatively flat terrace, above whose level stands the re¬ 
ceding front of the overlying formation, while in the opposite di¬ 
rection the lower formation has its terrace terminated by a similar 
front which drops down to the level of the formation next under¬ 
lying. Each formation then shows a receding front of the sort, 
the Theresa above the Potsdam, the Pamelia above the Theresa and 
so on. Because of the greater thickness of the formations the 
Trenton and Pamelia fronts are the highest and the most conspicu¬ 
ous as topographic features. The Trenton front only gets within 
the map limits in the extreme southeast corner of the Theresa 
sheet, but the Pamelia front can be followed as a cliff of more or 
less prominence across the Theresa and Clayton quadrangles, until 
the formation is lost beneath the river. This is the kind of topog¬ 
raphy invariably produced when a district of nearly horizontal 
rock formations of varying resistance is being worn down, but the 
general type is magnificently illustrated in the region here. 


GEOLOGY OF THOUSAND ISLANDS REGION 2 3 

The Pleistocene 1 

During the geologic periods of the Devonic, Carbonic and 
Permic, and the Mesozoic and Cenozoic eras, each millions of 
years in length, our area was doubtless always above the sea and 
subjected to the wasting processes of atmospheric erosion. 

Closing the immensely long time of erosion and bringing the 
history down to the present time, three geologic episodes are 
conspicuously recorded in the existing surface features. The 
first of these episodes was the burial of the entire area for some 
scores of thousands of years under the Labradorian ice sheet with 
its grinding flow. The second was the burial for further thou¬ 
sands of years under glacial and marine waters that immediately 
succeeded the latest of the ice bodies. The third episode is the 
present time, a restoration of the subatmospheric conditions of 
erosion, which has endured, probably, some 10,000 or 20,000 
years. 

It is now comparatively certain that during the long geologic 
history great changes of climate have occurred. The idea, once 
prevalent, that there had been during all geologic time a steady 
lowering of temperature and refrigeration of climate from a 
primitive condition of excessive heat and moisture is wholly an 
error. The oldest rocks of sedimentary origin contain records of 
glaciation. In the Permic, ice work was great and wide-spread, 
and glaciation was probably frequent during past time in elevated 
regions now eroded. The warm climate of the middle Tertiary was 
followed by glacial cold in northern lands, and all of New England, 
New York State and the basin of the Great Lakes was deeply 
buried under successive sheets of ice which had their origin or 
centers of accumulation in Canada and Labrador. The peculiar 
effects of the glacial invasions will be described in a later chapter. 

Following at least the latest of the ice sheets the entire area 
under description was buried for some thousands of years be¬ 
neath waters held up to high levels by the glacier acting as a 
barrier across the St Lawrence valley. The shore features and 
deposits characteristic of lake action are found over the region. 

During the time of the ice retreat this portion of the continent 
was lower, or nearer ocean level, than at present, and when the 
ice barrier melted away in the St Lawrence valley, the glacial 
waters (Lake Iroquois) were drained down to sea level, and the 
north and west sections of our area were long swept by oceanic 
waters, a branch of the Champlain (Hochelagan) sea called 


1 By H. L. Fairchild. 



24 


NEW YORK STATE MUSEUM 


Gilbert gulf. 1 The shores of the glacial and sea level waters 
are conspicuously preserved in many places, and specially in 
Jefferson county immediately south of the area; while their sedi¬ 
ments occupy the valleys [see pi. 29]. 

The slow tilting uplift of this part of the continent finally 
raised the Thousand Islands district above the ocean level and 
then Lake Ontario was initiated. The uplifting has continued 
until the outlet and lake are now 246 feet above tide. 

As the lake and marine waters were slowly drained away from 
the gently sloping surface of the area the storms and streams 
resumed their briefly interrupted work, and for a few thousand 
years they have again been gnawing at the rocks and land surface 
with important effects. 


THE ROCKS 2 
Precambric rocks 

The Precambric rocks of northern New York, as at present 
known, may be most conveniently classed in four groups, (a) 
a series of old sediments or rocks laid down under water, the 
Grenville series; (b) a series of granitic gneisses of igneous 
origin, which cut the Grenville sediments intrusively and hold 
abundant inclusions of them and which, in so far at least as the 
immediate region is concerned, are correlated quite confidently 
with the Laurentian granite-gneisses of Canada; (c) a series of 
somewhat younger igneous rocks which cut and hold inclusions 
of both the preceding groups, which have a great development 
in the eastern Adirondacks but occur in less force in the imme¬ 
diate region, and which consist of anorthosites, syenites, granites 
and gabbros, the last three of which occur here in masses of 
usually small size; and (d) of much younger igneous rocks, of 
late instead of early Precambric age, which appear as dikes of 
diabase or trap, and which have some development in the region, 
though less abundant than in the eastern Adirondacks. 

The Grenville sediments are the oldest known rocks of the 
region, and the fact that they are water-deposited rocks necessi¬ 
tates belief in the existence of a floor of older rocks on which 
they w r ere laid down. No certain trace of this old floor has ever 
been discovered in New York, and though it is possible that 
fragments of it may be contained as inclusions in the granite 
gneiss, we are as yet unable to distinguish such, if present, from 

1 Gilbert Gulf (Marine waters in Ontario basin). Geol. Soc. Am. Bui. 
17 712-18. 

2 By H. P. Cushing. 



GEOLOGY OF THOUSAND ISLANDS REGION 25 

the similarly situated inclusions of the Grenville rocks them¬ 
selves. the same conditions prevail in general over the much 
more extensive Precambric areas of eastern Canada. Recently, 
however, Miller and Knight have announced the discovery, in 
central Ontario, of a basement to the Grenville formation, Gren¬ 
ville limestone being found resting on an ancient lava flow, whose 
surface is thought to show signs of slight previous wear. 1 Miller 
and Knight correlate this old lava, or greenstone, with the oldest 
known formation of the upper lake region, the Keewatin, which 
consists mainly of greenstones, old lava flows and beds of frag¬ 
mental volcanic materials. There are present, however, some 
associated sediments, and Miller and Knight regard the Grenville 
as of Keewatin age. These are most important results and if 
future work fully establishes these correlations, it will follow 
that the Keewatin has steadily increasing sedimentary content 
and less and less volcanic material as it is followed eastward. 
By the time New York is reached the greenstones have entirely 
disappeared, so far as is known. At least no rocks similar to 
them have ever been discovered in the New York Precambric. 
It should also be stated that Adams is not disposed to accept the 
reference of the Grenville to the Keewatin on the basis of the 
evidence yet in hand, believing a reference to the next overlying 
group, the Huronian, to be more probable. 2 

However this may be, the difficulty of accounting for the dis¬ 
appearance of the old floor of deposit is not helped, but merely 
pushed a stage further back. Miller and Knight speak of only 
slight erosion of the old lava flow prior to the deposit of the 
Grenville limestone upon it. It is of course possible that this 
may be merely an interbedded flow of Grenville age and itself 
rest upon other Grenville sediments. But in any case these 
Keewatin lava flows and fragmental deposits are surface deposits 
and require the presence of a floor on which they were laid down 
just as much as do the Grenville sediments; but no such floor 
to the Keewatin is known. It is always found resting on Lauren- 
tian granite gneisses of igneous origin, or upon yet younger 
igneous rocks which invaded it from beneath in molten condition, 
cut it to pieces, and apparently engulfed and assimilated its basal 
portion along with the floor upon which it rested. Precisely 
these same conditions prevail in general in respect to the Gren¬ 
ville and its former floor. 

1 Bureau of Mines. Ontario. 16th An. Rep’t, pt 1, p. 22-23. 

2 Adams, F. D. Jour. Geol. 16:634-35. 



26 


NEW YORK STATE MUSEUM 


In New York then the Keewatin volcanics are wholly absent, 
except for the possibility that some of the amphibolite inclusions 
of the granite gneiss may be greenstone fragments considerably 
metamorphosed. Otherwise the Grenville sediments are the 
oldest recognized rocks, and they occur in patches or in belts of 
varying size and extent, resting on, surrounded by, and all cut 
to pieces by the granite gneiss and the yet later intrusions. 

Grenville rocks. These rocks as originally deposited con¬ 
sisted of limestones, shales and sandstones, both pure and in 
their various transitional phases. In all probability too there was 
some intermingled volcanic material, though the presence of such 
material has never been definitely proved for the New York 
Grenville. The rocks have been profoundly changed in char¬ 
acter since their formation, in part owing to great compressive 
stresses which operated throughout the district, and in part 
owing to the heat and pressure furnished by the great igneous 
intrusions, and also to the mineralizing agents to which these 
gave rise. These changes moreover were brought about early in 
Precambric time and under deep-seated conditions. As found 
today the rocks are wholly crystalline, having completely 
recrystallized under the severe conditions to which they were 
subjected, with loss of all traces of their original clastic textures. 
In their stead there has been developed a cleavage, or foliation, 
due to parallel arrangement of the mineral particles on recrystal¬ 
lization. The old bedding planes of the rocks can still be made 
out, however, in places where the composition of the original 
rocks changed, as where limestone was succeeded by shale or 
by sandstone, and from these old bedding planes it can be seen 
that the development of the foliation is parallel in direction to 
them. The original limestones have become coarse, white 
crystalline limestone or marble, the sandstones are now hard, 
glassy quartzites, while the shales and impure limestones and 
sandstones have become schists and gneisses of many types, 
while yet other varieties are contact rocks whose nature is due 
to action of the intrusives upon adjacent sediments. The variety 
of rocks is so great that it would be a hopeless task to attempt 
to map them all upon any such scale as that of the maps which 
accompany this report. One or more beds of very thick lime¬ 
stone occur, such as that along the Indian river northward from 
Theresa, or that along Butterfield lake; thick quartzites also 
occur, especially on Grindstone and Wellesley islands; a large 
thickness of green schists of a peculiar type is found to the south 



Grenville green schists near the St Lawrence at Forsters landing. Alexandria Bay quadrangle, 2F2 miles 
south of Chippewa Bay. Strike of schists n. 25 0 e. and dip 55 0 e. View looks north. H. P. Cushing, 
photo, 1908 






































































. 





























































































■ 








GEOLOGY OF THOUSAND ISLANDS REGION 


27 


and southwest of Alexandria Bay. But the bulk of the Grenville 
of the district occurs as a great schist series, with rather rapid 
alterations of varying types in bands of no great thickness, and 
interbanded with these are thin limestones and quartzites. After 
trial of various methods it was found that, on a map of this scale, 
and with rocks of this rapidly varying character, no further 
subdivision of the Grenville was possible than a separate map¬ 
ping of the thicker limestone and quartzite beds, the entire 
remainder being mapped singly as a schist formation. It is 
feared that even this amount of subdivision has resulted in a 
map too complicated for easy use. 

It was hoped that the careful, detailed mapping attempted 
might solve the problem of the order of superposition of the rocks 
and give some definite idea of the thickness of the whole. The 
outcome was disappointing and neither hope distinctly fulfilled, 
though some results were obtained. The mapping therefore is 
purely lithological and not on a structural basis, as it was 
endeavored to make it. 1 

The average trend, or strike, of the Grenville rocks is to the 
northeast. The direction to be sure varies considerably, swinging 
around to the north on the one hand, and to the east or even some¬ 
what to the south of east on the other, yet these variations are not 
sufficiently frequent to offset the general statement. The dips are 
usually high, seldom less than 45 0 and frequently very steep or 
even vertical [pi. 1, 2]. Over the greater part of the area north 
dips prevail, but are replaced by south dips throughout a belt of 
country from 2 to 3 miles broad across the Alexandria quadrangle. 
This is certainly indicative of folding of large magnitude, and is 
corroborated by the fact that in many localities minor folds are 
clearly to be made out, and intricate minor puckering and corruga¬ 
tion. Of the two broad limestone belts within the map limits, the 
one along the Indian river north of Theresa, and the one about 
Butterfield lake, the former has a north, and the latter a south dip, 
and in each case the breadth of outcrop across the strike is about 
a mile. With the steep dips a thickness of about 4000 feet is in¬ 
dicated for this limestone in each case, and it is therefore conjec¬ 
tured to be the same thick stratum, with the structure synclinal. If 
this be the true interpretation then the complex of quartzite and 

1 Though the work was of vastly more detailed character than the earlier 
work of Smyth on the same recks, it will be seen by any one who will take 
the trouble to compare the two maps that the basis for the subdivision.of 
the Grenville is substantially the same in each case. No more convincing 
testimony could be given as to the high class character of Smyth s work. 



28 


NEW YORK STATE MUSEUM 


schist, which lies between the two in the southeast corner of the 
Alexandria sheet, and which consists of alternating bands of quart¬ 
zite and various schists of no enormous individual thickness, but 
which, taken together, must have a thickness of several thousand 
feet, rests upon the thick limestone and is the youngest portion of 
the Grenville exposed within the map limits. To the north, and be¬ 
neath the limestone would come the great complex of green schists 
and impure greenish limestones which there occurs, which have 
steep dips and must have large thickness, at least as great as the 
two previous groups, and likely greater. Doubt is thrown, however, 
upon this interpretation by the fact that the rocks which follow the 
thick limestone to the south, on the Theresa sheet, differ consider¬ 
ably from the green schist series which follows it to the north on 
the Alexandria sheet, and yet according to this interpretation the 
two should be identical, representing the series directly beneath 
the thick limestone. Each does consist of schist, calcareous schist, 
and thin limestone bands, with an occasional thin quartzite, but the 
Theresa rocks are not of this distinct green schist type. A possi¬ 
ble answer to this objection may be found in the fact that, not¬ 
withstanding a rather intimate acquaintance with the Grenville 
series all over northern New York and in parts of Canada, the 
writer has nowhere else seen the counterpart of this green schist 
series. It is in rather close association with the Picton granite, 
which was richly supplied with mineralizing agents, and is every¬ 
where cut with numerous dikes from this granite, so that its pecu¬ 
liar characters are thought to be largely, or wholly attributable to 
this contact action, and thus explained as due to these local condi¬ 
tions. If this be not the explanation there seems no alternative 
but to regard the two thick limestones as separate beds, thus largely 
increasing the thickness of the section, already great. If the struc¬ 
ture is thus correctly interpreted, a thickness of at least 20,000 feet 
is indicated for the Grenville of the district, and this is a conser¬ 
vative estimate. If the structure is not synclinal this thickness 
must be nearly doubled. 

This matter will be discussed somewhat more in detail on a later 
page. The purpose here is simply to give,an outline of the sup¬ 
posed Grenville succession and some idea of the great thickness 
of the series. 

Limestones . The general Grenville limestone of the district is 
a coarsely crystalline and quite pure white marble, only sparingly 
charged with other minerals. The great bulk of the rock of the 
thick belt, or belts, just referred to, consists of 95$ or upward of 


Plate 2 



Road metal quarry in Grenville limestone at Theresa near the falls. 
The limestone bed is a thin one in the general schist series and the quarry 
face is down the dip, here 75°. At the upper part of the cliff is Potsdam 
sandstone with irregular contact with the limestone, and showing one of 
the depressed pockets characteristic of these contacts, filled with weakly 
cemented calcareous sandstone. H. P. Cushing, photo, 1907 


























































































































































































GEOLOGY OF THOUSAND ISLANDS REGION 


29 


calcite. Toward the edges, however, the rock becomes much less 
pure, and at times the same thing happens in the near vicinity of 
the igneous intrusions, large and small, which repeatedly cut through 
it. This is by no means the invariable rule however. In the case 
of the thin limestone bands which occur in the general schist series 
[pi. 2] there is much less pure limestone, since these bands show 
the same impure borders as does the thick belt, leaving only a 
small central thickness of the purer rock. In this pure rock oc¬ 
casional graphite scales, flakes of brown mica (phlogopite) and oc¬ 
casional small crystals of white pyroxene (diopside) are the usual 
accessory minerals and in very small amount. Others occur, but 
very sparingly. These rocks must originally have been extremely 
pure limestones, slightly contaminated with organic matter, which 
now appears in the form of graphite. 

The impure limestone of the area is owing to two distinct causes. 
Certain thin bands of impure limestone in the schist series, and the 
impure borders of the otherwise pure bands seem unquestionably 
owing to original deposit as shaly or sandy limestones, forming 
gradations between the pure rock and the overlying and underlying 
shales and sandstones. Hence on recrystallization a much smaller 
percentage of calcite and a much larger one of other minerals has 
resulted. The other cause is the interaction of the limestone with 
igneous rocks, producing what are known as contact rocks, in which 
certain added ingredients are supplied to the limestones from the 
igneous rocks and react with the limestone to form minerals which 
thus have a mixed origin. Such contact rocks are thus limited to 
the near vicinity of the igneous rocks. 

The two most common kinds of impure limestone of the first 
type in the region are the quartzose limestones, and the pyroxenic 
limestones. Much of the marginal limestone seems to have been 
sandy, and even to have contained thin layers of fairly pure sand¬ 
stone. This has recrystallized as quartz, partly in fine grain, form¬ 
ing a mosaic with the calcite, and partly coarser and in films and 
patches in the limestone. Each mineral at times contains inclu¬ 
sions of the other, they evidently recrystallized together, and the 
quartz evidently had the stronger crystallizing force. There is a 
considerable amount of limestone in the area which is a calcite- 
quartz rock, with little or no admixture with other minerals. 

Even more common is the pyroxenic limestone, where the cal¬ 
cite is accompanied by a greater or less amount of a white or a 
light green pyroxene. This is prone to alter to serpentine, a dull 
green, greasy to earthy looking mineral, producing a mottled green 


30 


NEW YORK STATE MUSEUM 


and white rock which is of common occurrence in the Grenville 
wherever known. In the writer’s experience this is far from being 
true of the quartzose limestone which occurs in much greater force 
here than is customary. 

Of the various Grenville rocks the limestones are much more 
yielding under compressive stresses than are the schists and quart¬ 
zites, behave more like plastic and less like brittle bodies, and hence 
change shape more readily. As a result rocks which much resemble 
coarse conglomerates are a frequent feature in the Grenville lime¬ 
stone. Frequent dikes of granite traverse it, many of which are of 
slender width. Under compression these are brittle under condi¬ 
tions which are sufficient to cause flowage in the limestone, hence 
the dikes fracture, the separate fragments are somewhat shifted in 
position and limestone is squeezed in between them. The same 
thing takes place where thin bands of quartzite or of schist are 
present in the limestone, as is frequently the case. These frag¬ 
ments of granite, quartzite or schist weather less rapidly than the 
surrounding limestone, and hence project somewhat on weathered 
surfaces, with considerable increase in conspicuousness, and the 
separate fragments surrounded by calcite give an admirable mim¬ 
icry of a conglomerate in appearance. 

In addition to the normal white limestone frequent patches or 
streaks of gray or blue limestone also occur in association with it, 
which outwardly look much more like ordinary limestone. This 
is in line with the further fact that all the Grenville rocks seem 
somewhat less severely metamorphosed than is the case with the 
equivalent rocks to the eastward. Even the white marble has at 
times a grayish or bluish cast, and does not average as coarsely 
crystalline as the eastern Grenville limestone. On the other hand 
limestone of these characters is commonly not so pure as is much 
of the white limestone, and these gray or blue portions often occur 
in such situation as to suggest that they are contact effects of 
igneous rocks on the white limestone. In some instances certainly 
the white limestone changes to gray adjacent to an igneous rock 
mass of good size, and in others gray patches in white limestone 
occur in direct contact with granite dikes, an unlikely situation if 
they are really less metamorphosed portions of the white limestone. 
It is also true, however, that some of the gray limestone is very 
pure, that in some places it has no discoverable nearness to any 
igneous rock, and that in general the contact action of the igneous 
rocks of the district upon the limestone has been but slight, though 
with local exceptions to this statement. With such arguments in 


GEOLOGY OF THOUSAND ISLANDS REGION 31 

mind it has seemed to the writer as though the weight of the evi¬ 
dence were in favor of the view that at least some of the gray and 
blue limestone was representative of the white in less metamor¬ 
phosed condition, and if some, then likely all. 

Nowhere else in northern New York has the writer met with 
Grenville limestone of this fine grained, darker colored type. A 
comparison is at once suggested with the district in Ontario re¬ 
cently described by Adams who has shown that a similar, though 
better marked change comes over the Canadian Grenville limestone 
when followed westward, a local development of bluish limestone 
in thin bands within the coarser white limestones. 1 The evidence 
seems to indicate that we have here in New York the first glimpses 
of a similar tendency. 

The consideration of the contact effects which the various igneous 
rocks have had upon the limestones is deferred until the igneous 
rocks themselves have been described. 

Quartzites. There are two belts of ponderous quartzites in the 
region, one on Wellesley and Grindstone islands, and the other in 
the district east of Redwood (Alexandria sheet). In both cases 
the quartzite is interbanded with various schists and amphibolites, 
in highly folded condition, so that the number of quartzite beds is 
uncertain, and whether there is more than one massive, thick quart¬ 
zite can not be positively stated. There is certainly a considerable 
number of thinner bands. Unless our interpretation of the struc¬ 
ture is wholly at fault, these two belts represent lines of outcrop 
of the same geologic horizon, and form the youngest rocks of the 
series exposed in the district. In addition to this main horizon 
there are also frequent quartzite bands found in the general schist 
series, and thin bands even occur at times with the limestones. 
The more prominent of such bands are indicated upon the maps. 

The ponderous quartzites are the most resistant rocks of Pre¬ 
cambric age in the region, and since they are interbedded with 
schists which are far weaker, the districts where they outcrop are 
quite rugged topographically, as Smyth pointed out io years ago. 
The quartzite ridges tower abruptly above the narrow valleys eaten 
cut along the schists. 

Since the rock is an altered sandstone, recrystallized under heat 
and pressure, and since sandstones often range in composition from 
a high degree of purity to those which are quite impure, either 
shaly, or calcareous, it is but natural to find much variation in the 
rock from place to place. The thick bands are chiefly constituted 


1 Adams, F. D. Jour. Geol. 16:623-24. 



32 


NEW YORK STATE MUSEUM 


of massive, coarsely crystalline quartz, running up to as high as 
90$ of the rock, though feldspars and accessory minerals are always 
present. The thinner quartzite beds are generally more impure, 
though containing layers of coarse, massive, quite pure quartzite. 
The impurer beds are often well foliated, consisting of alternate 
films of pure quartz and of other minerals, the former very resistant 
to the weather, the latter less so, so that on the weathered surfaces 
the contortions and puckerings of the complexly folded schist 
series are much more perfectly displayed than in any other rock 
type of the region. They are often very close jointed, especially 
near granite, weathering out into small blocks [pi. 3]. 

Much of the quartzite of the district is more or less permeated 
with brown, iron-stained spots, due to the weathering out of some 
mineral with iron in its composition. These spots vary greatly in 
abundance in different occurrences and different layers, and may 
have a fairly uniform distribution, or, in the foliated varieties, be 
confined to the films containing other minerals than quartz, giving 
a brown and white, banded rock. In some cases, notably those of 
the first type, the mineral removed seems to have been pyrite, a 
mineral of consistent occurrence in the quartzite; in other cases 
it seems to have been pyroxene, though even here probably oxidized 
pyrite was responsible for most of the yellow, iron stain. 

In texture the rock shows great variation, ranging from the very 
coarsely crystalline, glassy rocks, down to varieties which have a 
finely granular make-up. 

Next to quartz, feldspars form the most prominent mineral con¬ 
stituent, orthoclase, microperthite and oligoclase all occurring. 
Much variation in relative amounts of the two mineral groups is 
shown, but in the great bulk of the rock, quartz is in excess and 
usually greatly in excess. In some varieties white to light green 
pyroxene appears in quantity, when the feldspar retreats. There is 
considerable of such quartz-pyroxene gneiss in the region, the 
quartz usually constituting 75^ of the rock. Light brown mica 
(phlogopite) is sparingly present in much of the quartzite, and some 
varieties become quite micaceous. Pyrite is a frequent mineral, 
as has been stated. Zircon and titanite are nearly always present, 
and at times fine needles of rutile are abundantly included. 

Here and there in the region rocks are found which present a 
puzzling half way stage between quartzite and granite, so that they 
are likely to be classed, now with one rock, and again with the 
other, according as the observer comes upon them from quartzite, 
or from granite. In all cases where the relations could be worked 


Plate 3 



Grenville quartzite of the much jointed type showing its characteristic 
weathering. The Potsdam lies just above but shows poorly in the view. 
Locality near the south margin of the Alexandria Bay quadrangle, nearly ] 
mile south of Crystal lake, by the roadside. H. P. Cushing, photo, 1907 



















































I 











. 
























geology of thousand islands region 


33 


out such rocks either occur along granite-quartzite contacts, or 
else are included in granite. They are apt to show close set, block 
jointing, like the quartzite. They have been found only in asso¬ 
ciation with the granite gneiss. The field evidence seems to us 
strongly indicative of the fact that these are really intermediate 
rocks, in the sense that they represent quartzites in various stages 
of granitization; that the quartzite is being permeated, soaked and 
even digested by the granite. The character of the intermediate 
rock, the shading of the two into one another, and the field oc¬ 
currence of the intermediate stages, all point to this conclusion, 
and seem incapable of explanation on any other hypothesis. 

Amphibolites. The name amphibolite is a convenient, compre¬ 
hensive term for a group of rocks of gneissoid habit and dark color, 
composed essentially of hornblende and feldspars, with often consid¬ 
erable amounts of biotite or pyroxenes, and with accessory minerals 
of which magnetite is easily chief, and quartz and garnet of fre¬ 
quent occurrence. In respect to origin, the rock has long been a 
puzzling one since apparently identically appearing amphibolite 
might be produced by metamorphism from either igneous or from 
sedimentary rocks of the proper character. In a multitude of locali¬ 
ties in the Adirondacks it has been shown that gabbro intrusions 
(whose character and origin is rendered certain by a core of prac¬ 
tically unchanged rock) are largely changed over into amphibolites, 
every step in the process being open to inspection. Similar rela¬ 
tions have been shown in many localities in all continents. 
Also in the Adirondacks, wherever the Grenville series is exposed, 
bands of amphibolite of varying thickness are found so definitely 
interstratified with other Grenville rocks of unquestioned sedimen¬ 
tary nature, that there seemed no escape from the conclusion that 
the rock must have resulted from the metamorphism of a sedi¬ 
ment; and amphibolite of such origin is equally of world-wide dis¬ 
tribution. In addition it has recently been shown by Adams that 
amphibolite can also be produced on a large scale by the contact 
action of granite on limestone. Here are therefore three different 
modes of origin, and the rock may be either igneous, sedimentary, 
or a contact rock. Each occurrence of the rock must therefore 
be studied by itself, in so far as its origin is concerned. Amphib¬ 
olite of all three types is present in our district. 

Within the mapped area amphibolite has not the bulk and im¬ 
portance that it has in much of the Precambric district adjacent. 
There is much of it present as inclusions in the granite gneiss 
bathyliths and stocks, inclusions of much variation in size and in 


34 


NEW YORK STATE MUSEUM 


abundance. Frequent bands of it occur within the Grenville series, 
but these are usually of no great thickness. There is but little of 
the rock present to which an igneous origin may be definitely as¬ 
signed. There are small areas of such rock in the district north and 
northeast of Theresa, where a somewhat more heavily bedded am¬ 
phibolite occurs, which holds much pyroxene in addition to the 
hornblende, and which seems to definitely cut the limestone with 
which it is associated. There are, however, amphibolite bands in- 
terstratified with the same limestone, and the mass has been severely 
deformed, with the production of flow in the limestone and the 
fracturing of the amphibolite into blocks, making one appear to 
cut and be included in the other, but this does not seem to be a 
case of the sort. In our experience amphibolites which result from 
the metamorphism of gabbro, usually contain pyroxene in quantity, 
while those originating from calcareous shales are more apt to be 
micaceous and lack the pyroxene, but this is far from being an in¬ 
variable rule, and is only suggestive of origin, not demonstrative. 

The amphibolites interstratified within the Grenville series, and 
regarded as metamorphosed sediments, calcareous shales or some¬ 
thing of that sort, are mostly quite finely and evenly granular rocks, 
which have wholly recrystallized, and vary from very solid look¬ 
ing, dense rocks in which mica is but sparingly present, to very 
schistose, highly micaceous rocks, which rapidly break down under 
the weather. In most of these orthoclase feldspar is apt to predomi¬ 
nate over plagioclase, and much of the rock contains some quartz, 
the micaceous varieties often considerable. The manner in which 
the variations appear is itself highly suggestive of metamorphosed 
sediments which differed somewhat in character from bed to bed. 
Some of the rock contains garnets, in some cases reaching large 
size, but they are exceptional rather than the rule. 

The amphibolite of contact origin will be discussed under the 
general topic of contact rocks. 

Schists. Under this heading are included a large number of 
rock types, so many that it seems hopeless to attempt to describe 
all, or many of them. No doubt they have diverse origins. Some 
of them quite certainly-owe their present character to contact action, 
and no doubt contact action of varying kind, and in varying degree 
is in large measure responsible for the great diversity of the group. 
Some of the rocks grouped here are no doubt igneous, and in their 
character distinctly suggest such an origin, though the proof is dif¬ 
ficult to obtain. 

A very common variety of Grenville schist, the so called “ rusty 


GEOLOGY OF THOUSAND ISLANDS REGION 35 

gneiss ” with its characteristic yellowish tinge on weathered sur¬ 
faces, is but sparingly present in our area here. In the district 
cast of Redwood it occurs somewhat, as it does also to the north¬ 
ward of Theresa. It is a quartzose gneiss, usually containing the 
mineral “ sillimanite ” and holding pyrite in quantity, the easy de¬ 
composition of which is chiefly accountable for the weakness and 
the color stain of the rock. 

There are reddish, acid gneisses which, so far as composition 
goes might be either original granites, or shaly sandstones. There 
are black and white gneisses, which are feldspar-pyroxene-quartz 
gneisses. There are very granular, dark reddish, weak, microper- 
thitic feldspar-hornblende gneisses; gray, f eld-spar-hornblende 
gneisses, holding much pyrite and titanite; there are leaf-quartz 
gneisses, the quartz in coarse spindles or lenses, and with little 
other than feldspar in addition; evenly granular, white, spotted 
gneisses which are microperthite-quartz-hornblende rocks; garneti- 
ferous, quartz-biotite gneisses, with but little feldspar and a lot of 
pyrite; quartz-feldspar-phlogopite gneisses with graphite; gneisses 
which somewhat suggest metamorphosed volcanic tuffs, though in 
no case has it been possible to demonstrate such an origin for them. 
Many of the rocks contain calcite, which at times has resulted 
from alteration and at times suggests itself as an original constit¬ 
uent. Graphite is a frequent mineral in many of the schists. 

Nowhere in the district has a rock been found which at all sug¬ 
gests the greenstones of the Keewatin formation. 

Belts of badly altered rock, considerably impregnated with iron, 
so as to constitute lean iron ore, occur within the Grenville schist 
belts, striking with the belt and apparently behaving like an in¬ 
tegral part of the series. Fragments of one such belt are found 
in the granite of the Alexandria bathylith near Cranberry creek, 
and a prominent belt occurs east of Redwood, especially along the 
north side of Millsite lake. The rock is exceedingly weak, earthy 
looking, either red, or yellow brown in color, and has a consider¬ 
able local use for road metal. It is so thoroughly altered that it is 
almost impossible to get any clear notion of its original character 
being simply a mass of clayey, alteration products, with consider¬ 
able calcite, and the whole impregnated with hydrated iron oxid, 
chiefly the red oxid. There are fresher streaks and bunches here 
and there which appear to be granite gneiss. None of the so 
called “ serpentine ” rock, which is generally associated with the 
similar, but richer, belt of iron ore which runs through Antwerp 


2 


36 


NEW YORK STATE MUSEUM 


and Rossie, just east of our map, has been noted here ? but with 
that exception there is a strong resemblance in the material. 

Igneous rocks. Gneissic granites (Laurentian). There are two 
extensive (bathylithic) masses of granite gneiss in the district, 
both of which are only in part within the mapped area. The 
western end of what we have called the “ Antwerp bathylith ” 
is exposed on the Theresa quadrangle, disappearing westward 
under a Paleozoic cover. The Alexandria bathylith, on the main¬ 
land and islands of the Alexandria quadrangle, seems of smaller 
size but also disappears under a Paleozoic cover, both eastward 
and westward, and passes across into Canada as well. There are 
in addition numerous smaller masses. It is highly probable 
that all are connected underground, and represent the upper 
portions of a great, underground mass of granite, underlying all 
of the Grenville of the district, except where cut away by the 
later intrusions. 

That this granite came to its present resting place after the 
Grenville was deposited was pointed out by Smyth 10 years ago, 
and is shown clearly in a host of exposures. Dikes without 
number run out from the granite masses into the Grenville rocks, 
the granite is everywhere full of included fragments of the Gren¬ 
ville, and along the contacts between the two sets of rocks, the 
Grenville rocks have plainly been modified by the contact action 
of the intrusive. 

The general rock is a quite acid, red granite, composed chiefly 
of feldspars (microperthite, microcline and oligoclase) and 
quartz, with small amounts of mica (both biotite and muscovite) 
and magnetite, and with zircon, titanite and apatite as acces¬ 
sories. Such rock does not appear especially gneissoid, though 
usually of rather fine and even grain, but in thin section it 
invariably shows much crushing, and a considerable amount of 
recrystallization. The rock is everywhere cut by its own aplite, 
pegmatite and quartz dikes, some of which are much coarser 
grained, as usual. Many of the granite dikes which penetrate 
the Grenville, especially the limestones, are coarser grained, and 
less mashed than the general rock. 

In a minor way the rock of the bathyliths is quite variable, 
and that in two main ways, one apparently representing original 
variations in the rock, and one owing to relative abundance of 
inclusions and the effect of the granite on them. The rock varies 
from one which is almost wholly constituted of feldspars and 
quartz, to one which contains several per cent of mica, which 


GEOLOGY OF THOUSAND ISLANDS REGION 


37 


thus becomes a conspicuous constituent. The rock changes from 
deep red through lighter shades to nearly white. It varies also 
much in texture, from throughly solid looking, crystalline appear¬ 
ance to varieties which weather to a sugary, granular aspect. 

As usual in the Laurentian, inclusions abound, and as usual 
the bulk of these are of amphibolite. Quartzite inclusions 
also occur, but infrequently, limestone inclusions never. The 
amphibolite inclusions are found everywhere but always most 
abundantly near the margins, where they abound. In fact a 
sharp boundary line between the granite gneiss and the adjacent 
Grenville rocks can not be drawn. In passing from granite to 
sediments the inclusions show steady increase in number until 
they come to constitute 50$ of the rock, beyond which we find 
sediments cut by granite dikes rather than granite holding inclu¬ 
sions of sediments. This reduces boundary mapping to a matter 
of estimating equality or inequality in amount of the two rocks, 
or in drawing a boundary where no real one exists. An attempt, 
however, has been made to indicate, by convention, on the maps, 
the actual state of things found in the field. 

The granite dikes usually represent the extreme acid state of 
the rock. The main mass averages less acid, chiefly because of 
the inclusions and of the attack of the granite upon them. In 
its preliminary stages this usually takes the form of an injection 
of the granite in thin sheets along the foliation planes of the 
amphibolite, the so called “ lit-par-lit,” or leaf type of injection, 
producing a banded rock of alternations of igneous and sedi¬ 
mentary material. Then, here and there, the granite breaks out 
from the foliation planes and spreads through the rock adjacent, 
forcing its grains apart by the injection of a thin film of granite 
between. This process becomes more and more pronounced, 
until much of the rock is broken up into a granular mosaic of 
particles cemented together by granite films, producing what 
may be called the mosaic type of injection, as distinguished from 
the leaf type. A fine example of injection of this type is shown 
in plates 4 and 5. The injected rock is not amphibolite, but is green 
schist, a closely related rock, and the type of injection is identical. 
As a further stage, in both types of injection, the sharp bound¬ 
aries become blurred, and this shading of the two rocks into one 
another becomes more and more prominent until finally rocks 
result which seem unquestionably to be due to the complete 
digestion of the amphibolite by the granite, gray gneisses of 
distinctly intermediate composition. As would be expected 


3§ 


NEW YORK STATE MUSEUM 


these more advanced stages are usually found in the case of 
inclusions away from the near vicinity of the border. 

We have not, up to the present time, definitely classed any 
of the granites of northern New York as of Laurentian age. Just 
across the border in Canada however, where the rocks are identi¬ 
cal, this term is definitely applied to the granite gneiss of the 
bathyliths which invaded the Grenville series from beneath, 
broke it up into disconnected belts and patches and destroyed 
all trace of its floor. The absolute identity of the rocks and their 
relations, leads us to apply the name here to the granite gneiss 
bodies with much confidence in the wisdom and propriety of the 
correlation. Whether these Laurentian granites are recognizable, 
however, over any considerable part of the Adirondack 
region, in distinction from granites of later date, is*a much less 
certain matter, though we believe it to be the case. It is thought 
for example that what we have called the Saranac gneiss in 
Clinton county, and the Long Lake gneiss of that quadrangle, 
are in all probability of Laurentian age. 

Theresa syenite. This comparatively small intrusive mass lies 
to the southward of Theresa, in a valley floored by Precambric 
rocks, but walled in by Potsdam on all sides It is somewhat 
less than 2 miles in length and with a breadth of less than half a 
mile, so far as the exposures go; at the south it may have greater 
breadth underneath the Potsdam. 

The general rock is of medium coarseness and granitic texture, 
though always with evidence of mashing and granulation, and 
of gray to greenish color. Most of it is chiefly made up of feld¬ 
spars. It resembles in high degree the common greenish, augite 
syenite of the Adirondack region, is unhesitatingly classed with 
that, and is the only representative of that rock type within the 
mapped area. Like it, this rock is quite variable, becoming red 
and granitic looking on the one hand, and more basic with 
increase of black minerals on the other. Near the border some 
varieties become feebly porphyritic. 

Microperthitic feldspar is always the chief constituent of the 
rock. Some oligoclase is always present. Quartz varies from 
some 15# in the more granitic, red varieties, down to complete 
absence. Augite is the most prominent black mineral in the 
ordinary rock, with biotite usually and hornblende sometimes 
sparingly present; magnetite, apatite, titanite and zircon are the 
chief accessories, the apatite usually quite prominent, another 
feature which the rock has in common with the general Adiron- 


Plate 


9 




t 



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Plate 5 



Upper figure. Hand specimen of the green schist, injected by granite, 
shown in plate 4. The central band here is one of those which appear 
as uniform, white bands in that view; here shown to consist of schist 
thoroughly and minutely broken up by, and inclosed in the granite. 

Lower figure. Hand specimen of sheared, banded, acid gneiss from 
near the shore of Wellesley island, due west of Alexandria. Bay. Shearing 
has produced numerous, slight faults, the shear planes are solidly 
welded up by secondary minerals, and dikes of the Picton granite cut 
across these, these of course not showing in the specimen. H. P. 
Cushing, photo 




















* 




















































































■ 






























































































































































GEOLOGY OF THOUSAND ISLANDS REGION 


39 


clack syenite. In the most basic variety seen, these dark minerals 
constitute no more than 15$ of the rock, the remainder being 
feldspar with a little quartz. 

Granting the equivalence of the rock with the general augite 
syenite, its age is rather definitely fixed as one of the great 
intrusives of the region, younger than the Grenville and the 
Laurentian granite, and also younger than the anorthosite intru¬ 
sion. Since this latter rock is not represented in the district, and 
the only direct evidence of age seen in connection with the 
Theresa syenite is that it cuts the Grenville, this additional evi¬ 
dence is welcome. 

Alexandria syenite. The intrusive mass of syenite called for 
convenience by the above name, since nearly the entire mass is 
in Alexandria township, lies west and north of Redwood, with 
a major axis of nearly 6 miles, and with a greatest breadth of 
nearly 2 miles; this on the supposition that but a single intrusion 
is here represented, as is believed to be the case. It is possible 
that two intrusions are here in which case the southern one 
fourth must be separated from the rest. 

Much of the rock is considerably crushed, granulated and 
rccrystallized, converting it into an augen gneiss. The size of 
the augen, many of which are a half inch long, bespeaks either 
a very coarse grained rock originally, or a porphyry, the latter 
being regarded as most probable. These coarse augen gneisses 
are chiefly peripheral, and mostly at the south end of the mass. 
Centrally, considerable cores of much less mashed rock remain 
which, while of medium coarseness of grain, do not approach the 
coarseness of the augen. The bulk of the rock is an augen 
gneiss with small augen, and it may be that the coarse augen 
gneiss at the south should be separated from the remainder; the 
two seem, however, to grade into one another, and no evidence 
that one cut the other was found, except that in a few localities 
the coarse augen gneiss is cut by dikes of fine grained red granite. 
These seem rather acid for dikes from the syenite. It is possible 
that they are stray dikes of Picton granite. 

The least mashed cores show a rock of granitic texture and 
medium grain, composed chiefly of a reddish feldspar and black 
hornblende, the latter in sufficient quantity to give some of the 
rock a strong resemblance to a diorite. These least gneissoid por¬ 
tions always show much mashing, when seen in thin section, the 
feldspars being granulated at their margins, and the hornblendes 
fraying out into biotite scales. This change increases until 


40 


NEW YORK STATE MUSEUM 


finally we get a rock in which but few unmashed feldspar centers 
remain, the hornblende has entirely disappeared, and the rock 
is a finely granular aggregate of feldspars, mica scales, and 
some quartz. ' 

Of accessory minerals, apatite and titanite are prominent, the 
former being abundant for this mineral, and of good size, the 
latter usually rimming the magnetite, as well as occurring away 
from it. The feldspars comprise microcline, microperthite and 
plagioclase (oligoclase-andesine), with the latter somewhat in 
excess when the plagioclase in the microperthite is included with 
it. The quantity of the two, however, is not far from equal in 
most cases. There is little or no quartz in the least mashed rock, 
and the quantity steadily increases in the gneissoid varieties. 
Some of this increase is certainly due to reactions during recrys¬ 
tallization since quartz commences to appear with the appear¬ 
ance of biotite. On the other hand the rock varies somewhat 
in acidity and some of the quartz is unquestionably primary. 

The coarse augen gneiss at the south has much the same 
mineralogy as the remainder, though more quartzose and acid, 
approaching a granite in composition. Smyth holds the view 
that it is a separate intrusion from the main mass of the syenite, 
and older, having noted an exposure in which the syenite 
appeared to cut the augen gneiss. We did not have the good 
fortune to observe any such exposure, hence his positive evidence 
must outweigh our lack of such. Chemically also the augen 
gneiss is much more acid than the syenite, being remarkably 
like the Picton granite in composition. If the two are separate, 
the augen gneiss is the older, and both are younger than the 
Laurentian, while the Picton holds inclusions of the augen gneiss. 

This syenite differs considerably from the usual type of syenite 
of the Adirondack region, represented here by the Theresa 
syenite, both in general appearance and in mineralogy. Analyses 
and more detailed description will be given in a later section of 
this report. It is more gneissoid, giving the appearance of 
greater deformation than the Theresa syenite, and hence it is 
tentatively inferred that it is somewhat older than that. The 
appearance may however be entirely deceptive, since the one 
rock gives rise to abundant mica when deformed, and the other 
furnishes little or none, nor any other mineral which promotes 
foliation. Hence the same amount of deformation would produce 
a better foliated rock in the former case than in the latter, a 
rock which would appear more greatly deformed. 


GEOLOGY OF THOUSAND ISLANDS REGION 


41 


Piet on granite. This is the latest, most extensive, most inter¬ 
esting, and most important of the intrusives of the region. It is 
named from Picton island (called Robbins island on the map) 
where it is most extensively quarried. It is, however, best and 
most extensively exposed on Grindstone island and would have 
been named after it except for the fact that the whole name was 
too long, and the term “ Grindstone granite ” possibly misleading. 
It is extensively exposed also on the west end of Wellesley 
island. Abundant dikes of it appear on the mainland of the 
Alexandria sheet, cutting the Alexandria granite gneiss and the 
Grenville schists, but the main mass falls short of reaching the 
shore. It does reach the mainland on the Clayton sheet, how¬ 
ever, judging from the exposures of the Precambric inlier up 
French creek, and may have wide extent here under the Paleo¬ 
zoic rocks. Across the border in Canada it seems to have large 
extent, though it has not yet been differentiated from the 
Laurentian in mapping. If, however, we are correct in correlat¬ 
ing the granite at Kingston with this rock, a bathylith of consider¬ 
able extent is implied. 

The general rock is a rather bright red granite of quite coarse 
grain. It varies much in this respect however, and much of the 
border rock is of much finer grain, as is also true of the general 
run of the dikes which radiate out from the mass. To a certain 
extent this diminution in apparent size of grain is due to mash¬ 
ing, but certainly the major part of it is a primary difference. 

Red feldspars (microperthite, microcline and oligoclase) con¬ 
stitute 75^ or more of the rock. Considerable quartz is usually 
present and is frequently characterized by a slightly bluish cast, 
which makes a helpful diagnostic feature of the rock. Horn¬ 
blende and biotite are sufficiently abundant to show prominent 
black spots in the otherwise red rock. In the finer grained border 
varieties and dikes, these black minerals retreat, quartz becomes 
somewhat more prominent, and the rock appears more acid. 
The general rock, however, does not impress one as a particularly 
acid rock for a granite, and this impression is borne out on 
analysis (given in a later section). 

The rock of the inlier to the south of Clayton, and that at 
Kingston are correlated with this granite with some reserve. 
The Kingston rock is a red granite of almost identical appear¬ 
ance with this, agrees closely in composition, and the only hesi¬ 
tancy felt in the matter is owing to the distance separating the 
two areas. In all likelihood the rock can be carried across on 


42 


NEW YORK STATE MUSEUM 


the Canadian islands to the mainland and thence west to Kings¬ 
ton, but until this has been done some reserve must be felt in 
making the correlation. The rock near Clayton differs in con¬ 
taining no quartz, and in being somewhat more mashed than 
the generality of the rock. It is in fact an acid syenite rather 
than a granite. Otherwise the two are exceedingly alike, and 
since the granite itself is low in silica for a granite, approaching 
a syenite in that respect, but slight variation is needed to cause 
the disappearance of the quartz. 

It must be borne in mind, in inspecting the maps, that the 
boundaries drawn between the Picton granite and the Laurentian 
are in the highest degree conventional. They are of the same 
vague sort as those between the Laurentian and Grenville, but 
even more vague than those because of the similarity of the two 
rocks. The fine grained dikes of the Picton are exceedingly like 
the acid dikes sent out from the Laurentian, and it is almost an 
impossible matter to tell which rock is in excess. On the other 
hand the maps do show the chief areas of the two rocks, bring 
out the fact that the one is younger than the other, and show 
their relative distribution and extent as accurately as possible 
in rocks of this kind. 

That the rock is the youngest of the intrusives of the region 
is indicated in several ways. It shows less sign of mashing than 
do any of the others, that is its unmashed central core is rela¬ 
tively much larger. Besides its abundant inclusions of various 
Grenville rocks it contains also frequent masses of granite gneiss 
of Laurentian type, and sends abundant dikes into similar rock 
where bordered by it, as it is locally on both Wellesley and 
Grindstone islands; and also it contains inclusions of an augen 
gneiss which is absolutely identical in character with the rock 
of the Alexandria syenite. Such age for the rock then seems to 
us in the highest degree probable, though it falls somewhat short 
of actual demonstration. 

Dikes of the granite are thought to range widely in the rocks 
east and south, though no attempt to indicate this upon the 
areal maps has been made. They are believed to be numerously 
present in the green schist belts of the western part of the 
Alexandria quadrangle, and also in the granite gneiss of that 
quadrangle. Even as far east as Alexandria Bay broad dikes of 
acid, usually fine grained, granite occur abundantly, cutting the 
granite gneiss all to pieces, and often inclosing sharp inclusions 
of it. We have never seen inclusions of this type held abun- 


GEOLOGY OF THOUSAND ISLANDS REGION 


43 


dantly in the aplite dikes of the granite gneiss itself, and regard 
the granite of the dikes as likely Picton. 

1 he contact relations of this rock with those adjacent are of 
much interest. It was apparently richer in mineralizing fluids 
than any of the other intrusives, and gives rise to interesting 
contact rocks, to be described in the succeeding section. But 
the field relations are also most important and interesting. 

While mapping Wellesley and Grindstone islands it quickly 
caught our attention that the abundant inclusions with which 
the Picton granite is everywhere charged were arranged in belts, 
that is, along a given line the inclusions were all quartzite, along 
an adjoining line they were all amphibolite, along another 
nothing but granite gneiss inclusions appeared. It was also 
seen that these belts had northeast-southwest trend, concordant 
with the general rock strike of the region, and that further the 
individual inclusions to large extent retained their original 
orientation and dip, notwithstanding the intrusion. Our strikes 
and dips, read on the rocks in the field, gave absolutely con¬ 
cordant results as we passed from one inclusion to another, 
results also concordant with the readings obtained on the same 
rocks beyond the reach of the intrusion. We were able to map 
the original belts of Grenville quartzite and schist, and the 
intrusions of Laurentian granite gneiss, as accurately as though 
the Picton granite was not present, so little had they been dis¬ 
turbed by the intrusion. An attempt has been made to bring 
out these facts upon the geologic maps. We could only account 
for the phenomena on the assumption that we have exposed here 
the very roof of this portion of the bathylith, the abundant 
inclusions representing masses but just loosened from their 
original place, not greatly sunken, and preserving unimpaired 
their original orientation. If this be the correct interpretation, 
the locality furnishes a fine illustration of the general phe¬ 
nomenon. 

Other intrusions. While the above furnish the only examples 
of intrusions of considerable size in the region, there are many 
others of small size, mostly too small to map, and which it 
seems hardly worth while to describe in detail. These are chiefly 
of granite gneiss, and are regarded for the .most part as of 
Laurentian age, and as representing comparatively small upw r ard 
protrusions from the general roof of the great mass of Laurentian 
granite gneiss which is believed to underlie the entire district, 
except where broken through by the later intrusions. A good 


44 


NEW YORK STATE MUSEUM 


illustration is that of the granite gneiss in the extreme southeast 
corner of the Alexandria sheet, which forms a wonderful cliff 
along the Indian river. 

In quite a number of localities syenitic rocks were found, always 
of trifling extent, and with field relations wholly indeterminate. 

At the west end of the upper bridge at Theresa, is a small intru¬ 
sion of gabbro, which is but little mashed, and has some features of 
interest in that it recalls the anorthosites and gabbros of the general 
Adirondack region, and is the only representative of these rocks 
seen here. It is a dark colored rock, showing numerous, glittering, 
lath-shaped feldspars up to an inch in length, on broken surfaces. 
It is made up of feldspar (labradorite), augite, hypersthene and 
hornblende, with considerable magnetite, and a little pyrite and 
apatite as accessories. The feldspar constitutes from 60 to 70 $ of 
the rock. In composition therefore it is distinctly a gabbro, 
though with more abundant feldspar than the usual Adirondack 
gabbro. Yet, in spite of the coarsely lath-shaped feldspars the 
structure is more nearly that of a gabbro than a hyperite, recall¬ 
ing in this respect the anorthosite-gabbros farther east. 

Diabase. Cutting all the other Precambric rocks of the region, 
occasional dikes of trap rock are found. The fact that they cut all 
the other rocks shows that they are younger, but it can also be 
shown that they are much younger than the other igneous rocks, 
though nevertheless older than the Potsdam sandstone. They 
are found only in the form of dikes, which are lava-filled fissures 
that in general represent plugged channels of ascent of the 
molten rock, leading downward to some source of supply of the 
material, and tending upward toward the surface. The dikes have 
chilled borders, showing that the inclosing rocks were compara¬ 
tively cool and hence at no great depth beneath the surface at 
the time of solidification. Furthermore they show no sign of 
having undergone the kind of deformation which all the other 
igneous rocks have experienced in greater or less degree, a kind 
which takes place only at considerable depths. Since the dia¬ 
bases cooled much nearer the surface than the granites and 
syenites, a long time interval of surface erosion during which a 
considerable rock thickness was worn away from the surface, 
must separate the two. 

In the district mapped these dikes have a somewhat unequal 
distribution. They are most abundant on Grindstone island, seven 
having been noted there, mostly of large size, none of them less 
than 20 feet wide, and ranging from that up to 100 feet in the case 


GEOLOGY OF THOUSAND ISLANDS REGION 


45 


of the dike numbered i on the map. Two have been found on 
Wellesley island, the wider of which measures 30 feet. Seven have 
been found on the mainland of the Alexandria sheet, in rather 
widely scattered distribution, and in general much narrower. None 
have been observed on the Theresa sheet. Smyth has described them 
as abundant on the Canadian mainland and islands in the vicinity 
of Gananoque, hence in the near vicinity of Grindstone island, 
which would seem to have been the chief center of activity. For 
petrographic details the reader is referred to his account which, 
though based on Canadian material, also describes these accurately. 1 

The dikes trend in various directions, from northwest around 
through north to northeast. Smyth states that those seen around 
Gananoque trend chiefly to the north, and were all cutting granite. 
It is to be noted that all those trending northeast, in our district 
here, are cutting Grenville rocks with general northeast strike, while 
all the dikes cutting the igneous rocks trend north or northwest. 
This is also true of two of the dikes cutting the Grenville, but in 
both cases the Grenville is in comparatively small bulk, and entirely 
inclosed by igneous rocks. The dike directions are therefore appar¬ 
ently determined by preexisting structures in the rocks, by the strike 
in the Grenville, and by a joint set in the igneous rocks. Small 
masses of Grenville rocks did not suffice to change the direction of 
dikes passing across them, the igneous rocks here being the deter¬ 
mining factor. 

Though they give no evidence of having been severely deformed, 
yet the rock of the larger dikes does.show evidences of considerable 
pressure. Many of the feldspar crystals are distinctly bent, and both 
the feldspar and augite of the rock shows evidence of strain by their 
undulatory extinction. In this respect they contrast with the diabases 
of the eastern Adirondacks, which show no such strain effects. 
The eastern dikes also have chiefly east-west trends, differ somewhat 
in mineralogy, and are more numerous and widespread; and are 
also separated from this area by a wide region in which such dikes 
are absent. We seem here therefore to be dealing with a wholly 
different center of igneous activity, and a much less extensive one 
than that farther east. 

Owing to their size and comparative freshness these dikes have a 
potential value in the region as a comparatively accessible source of 
good road metal. 

Contact rocks . The contact effects of the igneous rocks upon the 
Grenville sediments, and vice versa, may be grouped under three 


1 N. Y. Acad. Sci. Trans. 13:209^14. 



4 6 


NEW YORK STATE MUSEUM 


categories, effects produced upon the igneous rocks themselves, 
effects of the igneous rocks upon the sediments whereby rocks of 
intermediate composition are produced, and effects produced upon 
the sediments by the injection into them of fluids from the igneous 
rocks, fluids rich in mineralizing agents, and of quite different com¬ 
position from the general mass of the igneous rock. 

Bleaching of granite by limestone. In the early stages of the work 
it was noted that, while granite dikes and knobs of all sizes were 
of frequent occurrence, cutting the Grenville limestone wherever 
exposed, in all cases the granite was white, nearly as white as 
the limestone in fact. The granite of the bathyliths is, however, 
uniformly of red color, as are also the dikes in rock other than 
limestone. This led to search for limestone contacts along the mar¬ 
gin of the Antwerp bathylith and of the smaller granite intrusions of 
the Theresa sheet, when it was found that in every case the margin 
of the granite, adjacent to the limestone, was turned white. It also 
proved to be the case in subsequent work that whenever, in passing 
over granite country, a whitening of the rock was observable, 
directly beyond crystalline limestone was sure to be found. It also 
was found that the general granite of the Antwerp bathylith had 
had singularly little contact effect upon the limestone, pure, 
unchanged limestone lying directly in contact with the granite in 
most cases, and that the dikes also had had no contact effects, so that 
the rather unusual condition was presented of granite-limestone 
contacts in which the granite was the rock showing contact effects, 
not the limestone. 

•Study of the white granite, both chemically and in thin section, 
affords no explanation of the change. The white granite is in 
general somewhat more acid than the red, but that is believed to be 
nothing more than an expression of the general fact that the dikes 
which radiate out from the bathyliths are more acid than the main 
mass, whether they be red or white (they are usually red in all rocks 
except the limestone), and that the granite also is apt to become 
more acid near the margins. A little tourmalin is sometimes devel¬ 
oped in the granite where white, but it also developed elsewhere. 
The change seems to consist merely in a decoloration of the feld¬ 
spar, changing it from red to white; that of course on the as¬ 
sumption that the red color of the feldspar is original and not 
a later coloring due to slight alteration. In that case, however, 
it is difficult to understand why both feldspars, of the white granite 
as well as of the red, should not have undergone the alteration; this 
seems in fact so highly improbable, that we seem justified in regard- 


GEOLOGY OF THOUSAND ISLANDS REGION 


47 


ing the color as beyond question original. The red color which so 
many feldspars possess is usually ascribed to ferric oxid, though in 
general without any definite proof in the matter. In such case the 
loss of color might be ascribed to simple reduction of the iron, but 
what reducing agent the limestone might furnish is a difficult prob¬ 
lem and greenish, rather than white, feldspar would likely result. 
Analyses of both white and red granites are given on a later page, 
where the matter will be somewhat further discussed. The chemical 
differences between the two rocks are but slight, and we are in 
doubt whether in any recognizable respect they are due to influence 
of the limestone. The field relations are, however, perfectly clear, 
and susceptible of no other explanation. 

Mixed rocks. Rocks which seem definitely of intermediate com¬ 
position between the intrusive and a sediment, to be due to the 
intimate penetration and final digestion of the latter by the former, 
and which show all stages in the process, occur as the result of action 
of granite upon amphibolite and upon quartzite. In the former the 
action is chiefly seen in the case of the amphibolite inclusions which 
so abound in the granite gneiss, and which are found in all stages of 
being first penetrated by films of the granite and later slowly 
absorbed by it. The process has already been described; so has the 
gradation of granite into quartzite which is found in some localities 
and which seems only explainable on the assumption of production 
of a border zone of true mixed rock between the two. 

Contact rocks. These, as here understood, result from the injec¬ 
tion into the sediment of fluids from the igneous rock which contain 
only certain of its constituents instead of all, and which may, and 
often do, differ very materially in composition from the rock itself. 
The injection is apt to be more or less local, here much, there little, 
or none at all; the injected fluid may differ in composition at 
different points along the border of the igneous mass; the bordering 
rocks themselves differ from place to place, and finally the various 
igneous masses are quite sure to differ among themselves in the 
character of their mineralizing fluids. Since we have here three 
separate granite bathyliths, to say nothing of the syenites and smaller 
granite masses, and Grenville rocks of great variety of composition, 
the opportunity for contact action oT diverse sorts is exceedingly 
good. 

Green schists in Alexandria. Reference to the geologic map of 
the Alexandria quadrangle will show, to the south and southwest 
of Alexandria Bay, three northeast-southwest ridges of Grenville 
schists. These are cut out on the north by the granite of the 


48 


NEW YORK STATE MUSEUM 


Alexandria bathylith, though there is a zone between the two in 
which exposures are poor and infrequent. They are separated 
from one another in part by tongues of Potsdam sandstone, and 
in part by low, marshy valleys in which no rock outcrops appear. 
The exposures, however, cover an area of several square miles, and 
extend to a distance of at least 3 miles from the edge of the bathy¬ 
lith. The schists are everywhere cut by dikes of granite, most 
numerously as the granite is approached. While chiefly of the Alex¬ 
andria granite gneiss, it seems to us that dikes of the Picton gran¬ 
ite are also present numerously, though it is difficult to arrive at 
certainty in the matter. Certainly they are present in the granite 
gneiss itself. Nowhere else in northern New York have we seen 
just this type of schists, except as occasional occurrences of small 
extent and bulk. We are disposed to regard them as contact rocks, 
produced by the action of the granite upon what were, prior to the 
intrusion, somewhat impure limestones. We are disposed also to re¬ 
gard the Picton granite dikes as especially influential in the action. 
It must be frankly stated, however, that there are certain difficul¬ 
ties in the way of this view, and they will be later summed up. 

The schists are well banded and foliated and range from light 
to dark green, or greenish black, in color. They are usually of 
finely granular texture though these alternate with somewhat 
coarser grained bands. These latter show poorer foliation and are 
mottled green and pink in color. Narrow, dark red bands some¬ 
times appear, due to subsequent infiltration of ferric oxicl. At 
times the green minerals become scant, and the rock then has a 
light red to pink shade. Narrow bands of black amphibolite and 
of finely micaceous schist also appear, and an occasional thin quartz¬ 
ite band. But the bulk of the series is of green schist. Granite 
dikes and dikelets abound everywhere, cutting across or parallel 
with the bedding, in the latter case often forming a good injection 
gneiss. The dikes are of fine, granite gneiss, of coarse granite, 
of yet coarser granite pegmatite, or of quartz, the first most abund¬ 
ant. 

In composition these green schists are essentially feldspar-pyrox¬ 
ene rocks, the latter of green color and responsible for the general 
hue of the rock. Actinolite is commonly present, and very abund¬ 
ant in some of the bands; it is the only amphibole noted in the 
schists, except in the occasional amphibolite bands. Epidote is 
often present, though far less common than the actinolite. Some 
layers hold frequent, small, light colored garnets. Small, scattered, 
black tourmalins occur throughout the rock in all exposures. 


GEOLOGY OF THOUSAND ISLANDS REGION 


49 


Small titanites abound in the rock, magnetite and hematite appear in 
varying quantity, with pyrite, apatite and zircon as other acces¬ 
sories. 

Quartz is present in many of the bands but seldom in any great 
quantity and often wholly absent. The feldspar is in part micro- 
cline and in part plagioclase (andesine-labradorite) ; some micro- 
perthite is usually found also, and often much feldspar not char¬ 
acteristically marked. 

In addition to the above minerals the rock nearly always con¬ 
tains calcite, and this in steadily increasing quantity as the dis¬ 
tance from the granite bathylith increases. The rocks from the 
schist inlier in the Potsdam due east from Omar, average 20 to 
25$ of calcite; in the long ridge just to the north of this it occurs 
in large, though somewhat less amount; while in the ridge north¬ 
west of this, and nearest the granite, much of the rock shows but 
little calcite, only the coarser, mottled beds having it in quantity. 
The calcite is coarsely crystalline, in sharply bounded individuals, 
and clearly formed at the same time as the other constituents of 
the rock. 

The mineralogy of the schists strongly suggests contact effects, 
the tourmalin, actinolite and epidote being especially suggestive in 
this respect, none of them being normal Grenville minerals, away 
from the immediate vicinity of igneous rocks. The green pyrox¬ 
ene also is an abundantly formed contact mineral in the Grenville, 
though not so distinctive of contact metamorphism as the others. 
These, with the constant presence of calcite, give an impression 
that we are here dealing with a limestone belt much changed by 
contact action, with the granite and pegmatite dikes which abund¬ 
antly penetrate the series as the source of the mineralizing fluids. 
The fact that these green schists, though here present in great 
bulk, are not a usual member of the Grenville succession in the 
general region, also suggests a local cause for their presence. It 
would seem that a series so thick could not but occur repeatedly 
elsewhere were it an ordinary member of the general series. Sim¬ 
ilar rocks do occur in small bulk in the general schist series north 
of Mill site lake, but their small amount here but emphasizes the 
bulk of the other occurrence. 

As opposed to this suggestion of contact origin, the breadth of 
the belt and the distance it extends from the granite margin, 
its general uniformity of character, whether in contact with a dike 
or at a considerable distance from one, whether near the 
granite margin or remote from it, (the only observed difference 


50 


NEW YORK STATE MUSEUM 


being in the amount of calcite, and that a very slow and gradual 
change), seem more suggestive of regional than of contact meta¬ 
morphism. On this view the belt would consist of original impure 
limestones and calcareous shales, metamorphosed to the pyroxene- 
feldspar-calcite combination, and with the tourmalin, actinolite and 
epidote alone due to the later contact action. While unable to 
definitely decide between the two, the first seems to us the more 
probable. It is possible that the granite is close in place under¬ 
neath the whole belt. In our view, then, the belt is due to the con¬ 
tact action of an especial granite, its localization being thus ex¬ 
plained, acting upon a limestone series of considerable thickness, 
and certainly somewhat impure at least, as shown by the bands of 
quartzite, amphibolite and mica gneiss within it. Part of the reg¬ 
ular Grenville succession of the area consists of alternating thin 
beds of limestone, various schists and an occasional quartzite, and 
it would seem as if such a combination might well be turned over 
into a group like that of the green schists by contact metamorphism. 
This would be all the more likely if acted upon by two successive, 
granite injections as is supposed to be the case here, since dikes of 
Picton granite are believed to be present. 

The coarse pegmatite dikes of the north schist ridge, which furnish 
well crystallized specimens of orthoelase and specular hematite, to 
be found in many mineral collections, have already been described 
by Smyth. 1 

Tourmalin contact zones in Alexandria. The Picton granite is 
found cutting Grenville quartzite and amphibolite, but no other 
members of the series, and the same is true of its known dikes; that 
dikes suspected to belong to it cut other members has just been 
seen. This granite seems to have been much more potent in tour¬ 
malin-forming capacity than any other granite of the region and 
its contacts with the Grenville on Grindstone and Wellesley islands 
are characterized by narrow tourmalinized zones which Smyth 
has clearly described, as follows: 

Along their margins these dikes frequently show much black 
tourmalin and this is usually most abundant in the very narrow 
ones, in which the imperfect crystals of tourmalin interlock across 
the entire width. At the same time the schists along the contact 
become impregnated with fine, granular tourmalin, producing 
strips and irregular areas of a lustrous black rock. The remarkable 
feature about these contact zones in the schist is their extreme ir¬ 
regularity in form and extent, and their entire independence of the 
magnitude of the accompanying dike. A dike of granite a foot wide 


1 op cit. p. r94. 



GEOLOGY OF THOUSAND ISLANDS REGION 51 

may have no contact zone, while a mere thread of granite a few 
feet distant, may be bounded on each side by a band of the 
tourmalin rock 2 or 3 inches wide. Again, the tourmalin, in¬ 
stead of forming a continuous band, appears in lumps and bunches 
of every conceivable shape, irregularly scattered along a dike, and 
sometimes extending several inches away, at right angles to the 
course of the dike. 1 

Tourmalin is also at times developed in the quartzite as well as 
the schists, but not in the same definite manner. It is not at all 
certain that dikes from the Alexandria bathylith are excluded from 
the category of rocks producing this contact effect. In many cases 
the dikes from the two bathyliths can by no possibility be distin¬ 
guished from one another. In addition to these bands and bunches 
of abundant tourmalin, developed in this localized fashion, more 
scattered crystals of tourmalin, of the same evident origin, range 
much more widely through the rocks. 

Smyth dissents from the view that the Picton granite was espe¬ 
cially influential in the formation of these tourmalin zones, and in 
other contact phenomena. He points out that, in his belief, the 
tourmalin zones are most abundant at the extreme east end of 
Wellesley island, quite remote from the Picton granite, though 
with the Alexandria bathylith near at hand; also that the Alex¬ 
andria bathylith is much nearer the Alexandria green schists than 
the Picton. He therefore regards the Alexandria bathylith as 
the most important granite of the region in producing contact ef¬ 
fects. We are not sufficiently certain of the truth of the opposite 
view to urge it, and simply chronicle the matter as one on which 
we mildly disagree. It is not a matter of great importance in the 
interpretation of the geology of the region, on the general features 
of which we are in absolute agreement. 

Contact amphibolites. Adams has recently shown conclusively 
that, in central Ontario, amphibolite occurs as a result of intense 
contact alteration of Grenville limestone by granite, limestones pass¬ 
ing into rocks in which pyroxene, hornblende, feldspars and scapo- 
lite appear in increasing quantity up to final disappearance of cal- 
cite and with final entire replacement of pyroxene by hornblende 
and scapolite by feldspar. 2 We have had the privilege of going over 
his territory with him, and fully agree in his conclusions. Per¬ 
haps the chief interest attaching to his work is the explanation 
thereby afforded of the abundance of inclusions of amphibolite in 
the Laurentian granite gneisses, where cutting the Grenville rocks, 


1 op cit. p. rgo. 

2 Adams, F, D. Jour. Geol. 17:7-18. 



52 


NEW YORK STATE MUSEUM 


the scarcity of inclusions of other types, and the invariable utter 
absence of limestone inclusions, notwithstanding the abundance 
of limestone in the formation. Beyond doubt many of these in¬ 
clusions represent limestone fragments altered in this fashion. In¬ 
tense alteration, however, seems necessary, and that perhaps fur¬ 
nishes a reason why the comparatively small fragments caught up 
in the granite mass are so uniformly changed over, while at the 
contacts the change is much less obvious, or common. In our dis¬ 
trict here we have amphibolite inclusions everywhere in the granite 
gneisses, but no instances of the conversion of pure limestone into 
amphibolite along the contacts, similar to those in Ontario. There 
are, however, one or two instances of similar alteration on a small 
scale, in connection with narrow bands of limestone and small 
granite intrusions. The most clearly shown of these is right in 
the village of Theresa, at the road metal quarry near the lower 
bridge. The rock quarried here is a contact phase of the limestone 
cut through and through bv granite dikes. The chief rock is green 
in color and consists of pyroxene, titanite, feldspars and calcite, the 
latter running as high as 50^ of the whole in the portions of the 
rock most remote from the dikes. In contact with these, however, 
the rock is black, consists chiefly of hornblende and feldspars, 
though with a little remaining pyroxene and calcite, and has nearly 
completed its transformation into amphibolite. Very near at hand 
is the pure limestone band shown in plate 2, and there can be little 
question but that the green rock of the quarry is an altered phase 
of that, and no question at all but that the green rock is changed 
into amphibolite by the granite. On a small scale then it is a 
change identical with that described by Adams. 

Contact rocks of the Antwerp bathylith. In so far at least as 
the portion of the Antwerp bathylith included within the mapped 
district is concerned, the contact action of this granite is but slight, 
and it would seem to have been quite deficient in mineralizing 
agents, though as effective in the production of mixed rocks as the 
other granites. The dikes and stocks of white granite run every¬ 
where through the limestones without affecting them any, except 
in trifling amount in a few localities, nor does near approach to the 
margins of the bathylith produce any observable change in the 
Grenville rocks. In the case of dikes of granite pegmatite however, 
some contact action is the rule, coarsely micaceous rocks being the 
usual ones produced. Locally the mica becomes very coarse and in 
well formed crystals, so much so that at one locality north of 
Theresa an attempt was made to mine it commercially. The mica 


GEOLOGY OF THOUSAND ISLANDS REGION 


53 


is of light biown color, in the coarser varieties very light brown, 
resembling muscovite, though it seems undoubted phlogopite. 1 
Scapolite is also an abundant mineral in these zones, a phlogopite- 
scapolite-calcite rock being the usual combination. This is not 
one of the customary types of Grenville contact rocks in the general 
region, though the common one here. 

There are two other types of contact rocks which occur in small 
quantity within the area here, though common enough elsewhere, 
which call for brief attention. They occur in the district east of 
Redwood where Grenville rocks of all types are cut by small gran¬ 
ite masses. One is a heavy, basic, black rock, weathering rapidly, 
and composed chiefly of green pyroxene and black hornblende, with 
a little graphite, considerable pyrite, and some 15$ of calcite re¬ 
maining. Heavy, pyroxenic rocks of this type occur throughout 
the Adirondack region at limestone contacts, though usually not 
so hornblendic as this rock. 

The other rock consists of large, gray green pyroxenes set in a 
felt of tremolite needles, with rather abundant pyrite as the only 
accessory mineral. Such tremolite rocks occur not infrequently in 
the Grenville, the tremolite quite commonly altering to talc. The 
especial interest attaching to this particular exposure is that the 
tremolite rock is developed at the contact of granite against Gren¬ 
ville rusty gneiss, and seems quite certainly a result of the con¬ 
tact action of the one upon the other. So far as we recall, just that 
type of contact action has not heretofore been noted in the region. 

Great Precambric erosion 

The Grenville rocks are the only Precambric sediments in the 
region, and are of very early Precambric age. The remaining rocks 
of this age in the district are all igneous, and there is no evidence 
that any later Precambric sediments were ever deposited here¬ 
abouts, though it is possible that some such were deposited and 
subsequently worn away. The Precambric rocks of the present 
surface, both sedimentary and igneous, present characters which, 
so far as we know, are only given to rocks under conditions of high 
pressure, and at least moderately high temperature, conditions which 
in general prevail only at considerable depths below the surface. 
All the igneous rocks except the diabases give evidence that they 
solidified well beneath the surface, and the deformation of both 
these and the sediments is of deep-seated type. It is, however, not 


1 It is of the second order and with very small axial angle. 



54 


NEW YORK STATE MUSEUM 


quite so prominently of this type as in the case of the corresponding 
rocks of the central and eastern Adirondacks. We are forced to 
argue that, when these rocks were deformed, a considerable thick¬ 
ness of other rock overlay them, which thickness was subsequently 
worn away. This surface wear goes on very slowly at best, and 
must have been continued through long ages, yet was completed 
before Potsdam deposition began. The time involved is many mil¬ 
lions of years, in all probability a rock thickness of at least a mile 
or two was removed, and yet at the close the region was pared 
down to a surface of comparative smoothness. Much Grenville 
has thus disappeared, the tops of the igneous bathyliths are gone, 
together with whatever of younger rocks may have been present 
above them. The diabases were intruded toward the close of this 
long period, since plainly they solidified not far beneath the surface. 

PALEOZOIC ROCKS 1 

The Paleozoic rocks of the district, for mapping purposes on 
maps of this scale, are separable into six quite distinct lithologic 
units, which in large part coincide with the subdivisions of these 
rocks made long ago by the early geologists of the State. These 
are, in order of age from below upwards, the Potsdam sandstone, 
Theresa dolomite, Pamelia limestone, and Lowville, Black River 
and Trenton limestones. Above the last named the Utica and Lor¬ 
raine shales come in, but these nowhere reach the map limits, their 
northerly boundaries being found on the Watertown and Sacketts 
Harbor sheets, next south. 

The basal member of this sedimentary series, the Potsdam sand¬ 
stone, was deposited upon the worn surface of the Precambric 
rocks, and in order to properly describe the sandstone it is neces¬ 
sary to present in some detail the character of this surface. 

Precambric surface underneath the Potsdam 

That the surface on which the Potsdam sandstone was laid down 
was far from being an even one was clearly stated by Smyth, in his 
report on the district. 2 

That a similar irregular floor is present in many parts of Canada, 
of the upper lake region and of northern New York, has been shown 
by many observers. There is therefore nothing novel in the features 
to be described, but they are worthy of somewhat extended descrip- 

1 By H. P. Cushing. 

2 N. Y. State Geol. 19th An. Rcp’t, p. rioo-i. 



Plate 



The “ granite knob ” country. View taken from nearly 3 miles southeast of Theresa, looking southeast, show- 
lg one large and several small knobs of the Antwerp granite bathylith. IT P. Cushing, photo, 1907 



























Plate 



A granite boss, Forsters landing, 3 miles east of south of Chippewa Bay, Alexandria quad¬ 
rangle. H. P. Cushing, photo, 1908 












































































GEOLOGY OF THOUSAND ISLANDS REGION 55 

tion since it is very exceptional to have the evidence as abundant 
and as clearly shown as it is here. 

Ihe evidence of surface irregularity is of threefold nature, ( a ) 
that given by exposures of direct contacts, (b) that given by the 
tracing of the lines of contact of the Potsdam and Precambric, even 
without exposures of the actual contact, and (c) that given by the 
topography of the present Precambric surfaces, since it can be 
shown that these surfaces are substantially those upon which the 
Potsdam was originally deposited; in other words that the Potsdam 
is just being pared away from the Precambric over part of the 
district, its numerous outliers testifying to its former presence over 
the whole and to the recency of its removal where now absent. 

Where the Potsdam has been removed the Precambric surface 
disclosed is one of low ridges and valleys, with general northeast- 
southwest trend. The ridges are low and with hummocky surface, 
and the valleys are broad and shallow, and developed on the weak 
rocks (such as the limestones and weak schists) or on lines of 
structural weakness (as along lines of sheared and shattered gran¬ 
ite). The extreme of relief does not much exceed ioo feet, and is 
generally less. The quartzites, resistant gneisses and some long 
and wide granite dikes constitute the ridges. In the relatively ele¬ 
vated country occupied by the igneous bathyliths the surface is of 
the knob and basin type [pi. 6 and 7]. The numerous granite 
dikes and small bosses which cut the limestone and are resistant to 
weathering, diversify the valley bottoms. Hence a large part of the 
area consists of slopes, and extensive flats do not appear. 

The surface underneath the Potsdam is precisely of this sort. 
The smaller Potsdam outliers are usually mere remnants remaining 
in places where the floor was lowest and the sandstone thickest. 
The larger outliers cover both high and low ground. The Pots¬ 
dam resists wear, and hence usually presents cliff fronts at its mar¬ 
gins, showing thicknesses of from 20 to more than 60 feet of sand¬ 
stone, yet even with these thicknesses the summits of the outliers 
are often overtopped by neighboring granite knobs. The evidence 
of the occasional inliers of Precambric. rocks in the Potsdam is 
even more obvious. The two small inliers east of Goose bay (Alex¬ 
andria quadrangle) along the road from Alexandria Bay to Chip¬ 
pewa Bay, have their tops at the same level as that of the sandstone 
plain in which they lie, yet a 20 foot thickness of sandstone shows 
at the Potsdam margin, just to the northward. This line of evi¬ 
dence might be pursued at great length but since it is less conclusive 
than are the other lines the above will suffice. 


NEW YORK STATE MUSEUM 



The second line of evidence is that obtained in following and 
mapping the long Potsdam boundaries. A single example, that of 
the Potsdam margin along the west bank of Indian river in the 
southeast corner of the Alexandria sheet and for i mile southward 
on the Theresa sheet, will serve as well as a multitude of illustra¬ 
tions to indicate what the evidence is. The section is convenient 
since it has a horizontal base, the edge of the Indian river marsh. 
The Potsdam faces the river in a prominent bluff which, when it 
comes down to the marsh level, as it frequently does, forces the 
pedestrian to take to the swamp, so that the walk is not recom¬ 
mended as a pastime. But the unbroken cliff margin renders accu¬ 
rate mapping of the Potsdam base possible, and underneath it Pre¬ 
cambric exposures are numerous. At the south end of this section, 
on the Theresa sheet, inspection of the map will show the Potsdam 
coming down to the river level in a point. Going northward it soon 
runs up the bank until the base is 40 feet above the river, with 
Grenville limestone outcrops showing beneath, then it returns to 
the river level and again rises, repeating the performance three times 
within a mile of distance. Soon after passing on to the Alexandria 
sheet the sandstone retreats prominently up the bank and back from 
the river, showing a 60 foot thickness of limestone underneath, then 
returns to marsh level, withdraws 30 feet up the bank, comes back 
again forming a point, retreats quickly for 60 feet up the bank and 
again returns to the river, all the while with limestone underneath, 
cut by occasional granite dikes, so that all these oscillations merely 
represent irregularities of the limestone surface. Northward from 
this last point of reaching the river, however, the limestone is cut 
out by granite gneiss, and this turns the Potsdam straight up the 
bank and out to the road, with a rise of more than 100 feet in the 
level of the Precambric surface. Equally striking are the oscilla¬ 
tions in level of the same margin when followed southward on the 
Theresa sheet, and this margin is easy to follow, using the railroad 
as a base. There are many other excellent examples, since this sort 
of thing is the rule throughout the district. The mapping of the 
Potsdam base is thereby rendered laborious but nothing can be 
imagined more beautifully demonstrative of the character of the 
surface on which the Potsdam rests and its identity with that of 
the surface from which the Potsdam has been removed. 

Lastly there is the evidence given by the actual contacts. There 
are quite a number of these, more than the writer has seen in the 
entire remaining border of the Adirondack region. Besides the 
actual contacts there are a host of others where but a few feet of 


Plate 8 



Contact of the Potsdam sandstone on Grenville quartzite by roadside 
i mile southeast of Redwood, looking west. The quartzite is somewhat 
contorted but its dips are not steep, from 20-30°. The upper view is from 
15 feet distance, the lower with the camera only 4 feet away and showing 
only the lower layer of the Potsdam clearly. H. N. Eaton, photo, 1908 





















































Plate 


a* 



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cg g G3 

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<u ,c 

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ns 

<v 

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bo 


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<u 

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(f) (L) 




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\ 















Plate io 



Upper view. Contact of Potsdam sandstone on Grenville limestone just 
north of lower bridge at Theresa, near the point at which plate n was 
taken. The Potsdam base rests against the side of a limestone hill, and 
the boy is seated on the limestone, with his hand resting on a portion of 
the Potsdam base from which the limestone has been removed. 

Lower view. Nearer view of a portion of plate 9 showing the rotted 
limestone and the portion of the Potsdam base which projects out beyond 
it owing to removal of the limestone. H. N. Eaton, photo, 1908 












GEOLOGY OF THOUSAND ISLANDS REGION 


57 


space intervenes. This is due in part to the many miles of Postdam 
boundary in the region and in part to the scanty glacial deposit and 
hence abundant rock exposures. Many of the exposed contacts 
are on slopes, and on limestone, and it is these that are most unusual 
and interesting. 

Plate 8 shows Mr Eaton's photographs of a contact on quartz 
schists, i mile southeast of Redwood on the Rossie road, a contact 
already described and figured by Smyth. The contact here is on the 
summit of a ridge of quartzite, hence is fairly horizontal where 
photographed, though the level drops away on each side at no great 
distance. 

Two fine examples of contacts on slopes occur within the limits 
of the village of Theresa, along with others almost as good. One of 
these is by the roadside a short distance west of the upper bridge. 
A high Potsdam cliff borders the roadway for a few rods, with the 
base of the formation well below the road level. At the west end 
the base comes up to the road level, the cliff sets back some 20 feet, 
and the base rises sharply to from 12 to 15 feet above the roadway, 
exposing impure Grenville limestone underneath. The recess faces 
north, and is beset with shade of trees so that satisfactory pho¬ 
tography is difficult, the view shown in plates 9, 10 being unsatisfac¬ 
tory. The surface of deposit has an angle of slope of 45 0 or more, 
and the soluble limestone has been somewhat eaten away from 
beneath the sandstone, so that several square yards of the actual 
basal surface are exposed. This is set with occasional quartz peb¬ 
bles, but these are sparse, and except for them the rock is quite like 
that above. The sandstone is very massive and irregularly bedded, 
with a semblance of parallelism to the floor of deposit as is usual 
with the basal Potsdam hereabout. 

The other contact mentioned is exposed on the north side of the 
river just above the lower bridge. The map shows a small Potsdam 
outlier there, whose narrow, southwest edge appears as a low cliff by 
the roadside [pi. 11 ]. The ground level falls toward the river and 
at the south end of the cliff the base of the sandstone is exposed, 
resting on Grenville limestone underneath. Plate 10 is a photo¬ 
graph of this contact. At the south the cliff bears sharply away 
from the road and by turning into the yard of the first house to the 
south a fine exposure of the south margin of the outlier is obtained, 
showing the Grenville limestone rapidly rising in altitude and car¬ 
rying up the Potsdam base with it. The limestone surface falls not 
only to the west but also to the north. As in the previous case a part 


58 


NEW YORK STATE MUSEUM 


of the sandstone base is exposed, owing to solution of the limestone 
beneath. A sketch of the relations here is given in figure I, the 



Fig. i Potsdam contact on Grenville limestone, just 
north of lower bridge at Theresa, showing the sloping 
Grenville hillside on which deposition took place, and 
the sand-filled cracks in the limestone. 

arrow showing the camera position for plate n. It is at this localit) r 
that the best examples of sand extending down into widened joint 
cracks in the Grenville limestone were seen. At the east end of the 
outlier the limestone is cut out by granite gneiss, whose summit is 20 
feet above the top of the sandstone, hence terminating the outlier in 
that direction. Of course the full original thickness of the sand¬ 
stone is not present in the outlier, but only the mere basal portion, 
and formerly the sandstone extended over the granite as well. 

Another interesting contact occurs along the Potsdam front, 2*/2 
miles northeast of Theresa. From a previous northeasterly trend 
the front here turns and for a mile and more runs northwest across 
the strike, crossing a prominent granite ridge and then dropping 70 
feet in level into a limestone valley. Near the turn the contact 
sketched in figure 2 is shown. A low knob of ferruginous, quartz 
schist projects upward into the Potsdam to the amount of 20 feet. 



Fig. 2 Potsdam contact on Grenville quartz schist, 
miles northeast of Theresa. The much contorted 
and steeply dipping schists constitute a ridge over 20 
feet high around which the Potsdam was deposited. 


The Potsdam here is more evenly bedded than in the cases described 
at Theresa, the bedding abutting squarely against the sides of the 
knob. Its small size as compared with the long ridge slopes of the 
other contacts is thought to be the chief reason for this difference. 


























GEOLOGY OF THOUSAND ISLANDS REGION 


59 



Fig. 3 A nearer view of a portion of the 
contact showing a local steep slope of the 
hill and projecting cornice of an extra re¬ 
sistant quartzite layer. 


There is an occasional quartzite pebble along the contact, otherwise 
the sandstone is normal, and gives no sign of basal conditions. 

Around to the left the slope of the knob steepens. There are 
occasional bands of coarsely crystalline, purer quartzite in the schists 
which are far more resistant to weathering. On this steep front one 
such layer projects as a cornice 
with the sand-filling beneath, as 
shown in figure ?. Photographic 
attempts here proved wholly un¬ 
satisfactory. 

Besides the contacts on larger 
slopes, of which the preceding are 
instances, there are a number of 
minor examples of the sort, chiefly 
as filled hollows of the limestone surfaces. A sand-filled hollow of 
the sort appears at the top of the limestone quarry near the Theresa 
boat landing, and is shown in plate 2. In the section there shown the 
hollow is about 6 feet deep and with twice that width at the top. 
Another example may be seen at the quarry just south of the 
Theresa depot, though the overlying sandstone is gone except for 
the small residual patch resting in the hollow so that its original size 
can only be guessed at. A considerable number of other examples 
have been seen, some merely sand-filled, others containing rock frag¬ 
ments as well. In all cases the cement is calcareous and the rock 
weak and easily removed. 

The above evidence of the character of the surface on which the 
Potsdam was deposited, is of precisely the sort so convincingly set 
forth by Wilson in his discussion of similar features in Ontario. 1 
In New York these features are developed in a belt of considerable 
breadth across the strike, showing a great number of ridges and 
valleys, with patches of overlying Potsdam, and with the relief in 
every case owing to differential erosion on rocks of varying resist¬ 
ance, and in no case to subsequent folding. In this State 
exposed patches of residual materials resting on the old surface are 
more numerous than in Ontario, and these are in the depressions in 
all cases, showing that the depressions were in existence and served 
as receiving pockets for this material at the commencement of sand¬ 
stone deposition. The evidence is abundant, clear and convincing 
that the Precambric surface underneath the sandstone is precisely 
like that where the sandstone is absent, and that the present topogra¬ 
phy of the Precambric areas is that resulting from recent stripping 

1 Wilson, A. W. G., Can. Inst. Trans. 7:146-55. 





6o 


NEW YORK STATE MUSEUM 


away of the sandstone; in other words that it is the reappearance at 
the surface of a topography of tremendous antiquity. 

It further shows that this surface was little affected by the ice 
sheets of Pleistocene times, otherwise this identity of character could 
not have been so well retained. 

Except for the local accumulation of a very scanty amount ot 
residual material in small pockets in the depressions (and this almost 
exclusively quartzose) the Precambric surface, as it passes under 
the Paleozoics, is remarkably free from signs of surface decay, 
even the weak rocks being astonishingly fresh. In this respect also 
the conditions are like those noted in many places in Canada and 
the United States, as described by numerous observers. 

The relief of the Precambric surface under the Potsdam is much 
the same in character here as elsewhere along the northern and 
eastern borders of the Adirondacks, but is apparently less in amount 
than it is further east, where there are differences in level of three 
or four hundred feet at least. The evidence there, however, is com¬ 
plicated by the presence of numerous large faults and is by no 
means so well shown as it is here. On the south border, in the Mo¬ 
hawk valley region, the surface was much smoother than here, ex¬ 
ceedingly smooth in fact. 

Potsdam sandstone 

The first deposits laid down upon the worn Precambric surface 
consisted of medium grained, quite pure quartz sand, now firmly 
cemented to sandstone. On the Alexandria quadrangle the forma¬ 
tion attains a maximum thickness of about 125 feet. This thickness 
diminishes both southward and westward, but shows a steady in¬ 
crease to the eastward of the area mapped. Within that the thick¬ 
ness of the sandstone is not greatly in excess of, or else does not 
quite equal, the variation of level shown by its floor, so that it is 
subject to continual variation from place to place, and thins to 20 
feet or less over the old ridge summits. On the Theresa quad¬ 
rangle, and on Wellesley island, it locally failed to overtop the 
highest of these, and the Theresa dolomite is found resting directly 
on the Precambric. 

The bulk of the formation consists of a very pure quartz sand, 
quite thoroughly cemented with a silicious cement. The general 
color is light gray to buff, weathering white, but in the northern 
portion of the mapped area there is much red, or banded red and 
white rock in the lower half of the formation. The bulk of the 
formation is evenly bedded, and the greater part is thick bedded, 


Plate ii 



Potsdam sandstone in Theresa village just north of the lower bridge. Just to the right of the view its 
contact with the underlying Grenville limestone is exposed, the contact being on an irregular and slop¬ 
ing surface. The view illustrates the very irregularly bedded character of the Potsdam in such situa¬ 
tions, which is certainly in part due to the irregularity of the floor on which it was laid down. H. P. 
Cushing, photo, 1906 





























t 










































































Plate 



Railroad cut in Potsdam sandstone 2 miles north of Theresa, looking east. Note its evenly bedded char 
actei as compaied with plate 10, also the slight dislocation toward the right. H. P. Cushing, photo, 1907 















Plate 




Potsdam sandstone, Gildersleeve quarry, near Rideau, Ontario; red sandstone, somewhat banded with white. An 
excellent example of the “tree concretions” shows midway in each view. Right-hand photo by H. M. Ami; left- 
hand photo by Geological Survey of Canada. 








■ 


. 

' 








GEOLOGY OF THOUSAND ISLANDS REGION 6l 

with thinner bedded upper portions; where deposited on sloping 
surfaces the lower portion is often very massive, and quite ir¬ 
regularly bedded with a rude tendency to conform to the surface 
of deposit [pi. ii, 12]. Cross-bedding is present somewhat but 
in by no means prominent development. Ripple marks, however, 
abound. Much of the silicious cement has been deposited as 
secondary enlargement of the original quartz grains, the slides fur¬ 
nishing some beautiful examples of this. 

Occasional long, cylindrical concretions (?) of a telegraph pole 
type appear in the sandstone, and are called “ tree trunks ” by the 
populace. As seen in cross section on rock surfaces they appear 
as circular portions of the rock, from 1 to 3 feet in diameter. On 
cliff sides they are long, vertical cylinders of sandstone. There 
is no perceptible difference in composition between them and the 
adjacent rock, but in every case the two are sharply separated by 
what may be for convenience styled a circular joint. No tendency 
to taper at the ends w T as noted, but the actual terminations were 
in no case seen. They certainly reach a length of 20 feet and may 
be considerably longer. Unless they represent a type of concre¬ 
tionary structure, we are wholly at a loss to account for them. 
If so they certainly are an unusual type both because of size and 

0 

shape, and because of having the same composition as the inclos¬ 
ing rock. In plate 13 is shown an excellent example of one of 
them, in the Potsdam sandstone at Rideau, Ont., seen by us in 
1908 under Dr Ami’s guidance. This has been already described 
by the Canadian geologists, and is here introduced because, while 
corresponding precisely to the New York examples, it furnishes a 
much better illustration than any there seen. 1 

Only at the base and the summit does the sandstone vary from 
these general characters. Basal conglomerates are present in but 
scant amount, with small thickness and patchy distribution. The 
majority of contacts show only a few, scattered quartz or quartzite 
pebbles in the basal layer of the sandstone. There are, however, 
frequent patches of coarse, basal conglomerates, especially on the 
Theresa quadrangle. They seem in all cases to occupy local hol¬ 
lows in the limestone valley floors, and to occur only where the 
limestone contained thin quartzite bands, or granite dikes. The 
pebbles are all sizes up to that of the fist, and show little or no 
rounding in most cases, being usually very angular. They con¬ 
sist chiefly of quartzite and of white granite, though in some cases 
pebbles of red, quartzose sandstone also occur. The cement is 


1 Ells, R. W. Roy. Soc. Can. Trans., ser. 2, v. 9, § 4, P- 103. 



62 


NEW YORK STATE MUSEUM 


calcareous in all cases. The angular form of the pebbles is due 
to the close jointing of the quartzite bands and granite dikes in 
the limestone, and the trifling amount of wear exhibited points 
to residual accumulation in the hollows, whereby they were pro¬ 
tected from abrasion. The very small supply of such material, 
taken in conjunction with the small amount of decay shown by the 
underlying rocks, is a factor of much significance. 

On the Alexandria quadrangle, both on the mainland and on 
Wellesley and Grindstone islands, a more extensive and bulky con¬ 
glomerate occurs, which has already been described by Smyth [see 
pi. 14] d The most impressive display of this conglomerate known 
to us is that in the cliff along the St Lawrence in the extreme north¬ 
east corner of the Alexandria sheet where, rising sharply from the 
river level it reaches a hight of 20 feet above it. Here, as usual, 
the deposit has a calcareous cement which dissolves away, loosening 
the cobbles, and giving an exterior resemblance to a cobbly mo¬ 
raine, while the adjacent river bottom is solidly paved with the 
material which has already weathered out. The deposit is every¬ 
where very coarse, a cobble deposit rather than a gravel. In the 
exposure here the cobbles run up to a foot in diameter, and average 
probably 3 inches. They are round to subangular and consist ex¬ 
clusively of Grenville quartzite. Smyth notes the presence of a 
few small pebbles from the tourmalin contact zones, but agrees 
in asserting the entire absence of granite and schist material, 
though several of the conglomerate outcrops rest on these rocks. 

In addition many of the exposures show that the conglomerate 
is not strictly basal, but has pebbleless sandstone beneath, up to a 
thickness of at least 10 feet ; and in all cases the abrupt transition 
from sand to coarse cobble at both upper and lower contacts is one 
of the most interesting features of the deposit. Its coarseness, its 
abruptness, its horizon, and the lack of variety in material of the 
cobbles render it an exceedingly difficult deposit to explain. 

There occur, in a few localities on the Theresa quadrangle, small 
patches of a dark red, very thoroughly indurated and vitreous 
sandstone which thus differs from the general run of the sand¬ 
stone of the district, though similar rock occurs in the formation 
elsewhere, as in the Clarkson quarry at Potsdam. As it occurs here 
it seems to be distinctly older than the general formation. All seen 
of it was absolutely basal, nowhere was the thickness as great as 1 
foot and it is only visible at actual exposures of the Potsdam 
contact on the Precambric. But all the sand-filled cracks seen in 


1 op. cit. p. rgg. 



Plate 14 





















GEOLOGY OF THOUSAND ISLANDS REGION 


63 


the Grenville limestone were filled with this type of sandstone, and 
it occurs frequently as pebbles in the otherwise basal conglomer¬ 
ates, being the only sort of sandstone occurring as pebbles in such 
situation. 1. he thorough induration seems certainly to have taken 
place before the pebbles were formed. There seems no way to ac¬ 
count for these conditions except to assume that there was an 
earlier deposit of sand in the district, likely in no great amount, 
and chiefly in the Grenville hollows, deposition ceased, thorough 
cementation followed and then erosion; in other words that there 
was a slight amount of deposition here in earlier Potsdam time, 
separated by an erosion unconformity from the bulk of the forma¬ 
tion. 

Occasional beds of black, and of mottled black and white sand¬ 
stone appear in the upper part of the formation. The coloring 
matter is entirely in the cement, which is silicious, and is wholly 
discharged at a low red heat, hence likely organic. 

In the uppermost 10 to 15 feet of the formation calcareous ce-. 
ment reappears, foreshadowing the change which gave rise to the 
overlying dolomite formation. In consequence of this the rock 
weathers easily to a weakly holding, brownish sand, usually mottled 
with spots of deeper brown. This portion is mostly thin bedded but 
terminates above in a very massive layer, 2 feet thick or more, which 
is comparatively resistant owing to its massiveness; and this heavy, 
brown mottled layer often full of small, rounded sand concretions, 
makes a convenient summit for the formation, owing to its rela¬ 
tive prominence. The first layer of gray dolomite usually comes in 
directly above, and if not, no more than a foot or two of sand¬ 
stone intervenes. The two formations grade into one another, so 
that any line of subdivision must be an arbitrary one. We have 
drawn it at the base of-the first dolomite layer to appear, and this 
closely corresponds with the summit of this thick sandstone. There 
is, however, some reason for the belief that the base of the upper,* 
calcareous sandstones should be made the division line. 

With the exception of the long trails of an unknown animal, to 
which the name of Climactichnites has been given, some of which 
have been found in the sandstone 1 mile west of Theresa, no fossils 
have been found in the formation in this district except in these 
upper, calcareous beds. 1 In these a large linguloid shell (iden¬ 
tified by Ulrich as L i n g u 1 e p i s acuminata) is quite com¬ 
mon, and passes up into the lower beds of the Theresa formation. 


1 Woodworth, J. B. N. Y. State Pal. Rep’t 1902. p. 959-66- 



6 4 


NEW YORK STATE MUSEUM 


Theresa and Tribes Hill formations 

These formations, as mapped, consist chiefly of rather thin bedded 
layers of blue gray, sandy magnesian limestone which are exceed¬ 
ingly tough and resistant rocks when fresh, but weather rapidly 
to an ocherous, rotten stone [pi. 15]. The basal portion, through a 
thickness of 15 feet, carries frequent beds of weak, calcareous 
sandstone in alternation with the limestone, the sandstone being 
identical in character and appearance with that forming the sum¬ 
mit of the Potsdam. These form apparent “ passage beds ” between 
the sandstone and the limestone above. The overlying beds consist 
chiefly of magnesian limestone though occasional sand streaks con¬ 
tinue throughout, and there is a varying and, in general, consider¬ 
able amount of sand in most of the beds. While this tends to have 
a streaky distribution, it seldom wholly gives out. The sand is 
chiefly of quartz, certainly 90$ of it consisting of that mineral, but 
grains of feldspar, mica, magnetite, pyrite, titanite and zircon are 
also present and all in quite fresh condition. 

All the rock effervesces freely with acid, and the thin section 
shows this to be chiefly due to the presence of calcite cement, most 
prominent in the more sandy portions of the rock. A prevailing 
and highly characteristic feature of the rock is the appearance, on 
freshly broken surfaces, of lustrous calcite cleavages. These are 
due to the coarsely crystalline character of the calcite cement, the 
crystals ranging from Ft inch to 1 inch in length, and inclosing 
a number of sand grains, so that they are veritable sand crystals. 
This lithologic peculiarity is a feature of the rock of this horizon 
across the entire northern border of the Adirondacks. 

As mapped the general thickness of the formation over the 
district is from 60 to 70 feet, but the thickness is variable. The 
thickness steadily diminishes to the west and to the south in 
the same fashion as the Potsdam’s. But there are also local 
variations in thickness which are to be ascribed to wear of its 
summit during an erosion interval which separated its completed 
deposition from the beginning accumulation of the succeeding 
formation. For instance it has a thickness of but 20 feet near 
the north end of Perch lake (Theresa sheet) though recovering 
its normal thickness of 60 feet both to the east and to the west: 
and that the diminution in thickness is because of the wearing 
away of its upper beds with the production of a shallow valley 
is shown by the fact that the overlying formations thicken here 
by the same amount that the Theresa thins, and that the thicken- 


Plate 15 







Tribes Hill limestone in creek wall 1 mile west of Lafargeville, looking west. The fairly massive beds, 
ith their tendency to weather into thinner bedded form are well shown. Hight of section 15 feet. 
. P. Cushing, photo, 1908 


















. 



































' 




















































GEOLOGY OF THOUSAND ISLANDS REGION 65 

ing is due to the presence of basal layers which disappear to the 
east and west as the Theresa thickens. 

The field work in the district Avas completed, and this report 
written under the impression that this comparatively thin forma¬ 
tion was a unit and all of the same age. In its lower portion Lin- 
g u 1 e p i s acuminata is abundant; above, specimens of a 
rather large, flat-coiled gastropod occur abundantly in places; 
occasional cystid plates are found, and unrecognizable traces of 
other forms. The horizon seemed the same as, and the beds 
identical with beds which directly overlie the Potsdam sandstone 
all across northern New York, a length of outcrop of 150 miles, 
and which have heretofore been called “ passage beds ” between 
the Potsdam and the Beekmantown, the Beekmantown being the 
formation which overlies the Potsdam for much of this distance. 
In the belief that no Beekmantown was present here, and yet 
that there was here a formation which required mapping separate 
from the Potsdam, the name Theresa was proposed for this 
magnesian limestone formation, it being well exposed in the 
township of that name. 1 Recent work by Ulrich, Ruedemann 
and myself in the Mohawk valley has, however, tended to throw 
much doubt upon the entire correctness of this position. We 
find that the formation in the Mohawk vallev known as the 
Little Falls dolomite, and heretofore regarded as of Beekman¬ 
town age, is made up of two unconformable formations, the 
uppermost of which is of lower Beekmantown age, and is a quite 
fossiliferous limestone which we are proposing to separate and 
call the Tribes Hill formation; while the underlying dolomite 
formation is of Upper Cambric (Ozarkic) age. Now the Tribes 
Hill formation contains, as one of its fossils, a gastropod (named 
Pleurotomaria hunterensis by Cleland) which 
Ulrich regards as identical with the gastropod from the Theresa 
formation; it also contains numerous cystid plates, and these 
he also regards as identical with those from the Theresa. The 
Lingula, however, occurs in the Little Falls dolomite, instead of 
the Tribes Hill formation, and is in fact a characteristic Ozarkic 
fossil all around the Adirondack region. Ulrich’s present view 
is therefore that the Theresa formation, as here mapped, is in 
part of Qzarkic, and in part of Tribes Hill (lower Beekmantown) 
age. If this be true there must be an undetected unconformity 
between the two portions. In the field the only lithologic 
difference noted between the upper and lower portions of the 


1 Geol. Soc. Am. Bui. ig:i55 _ 7d. 







66 


NEW YORK STATE MUSEUM 


formation was the absence above of the sandstone beds which 
are interstratified with the limestones in the lower division. 
Otherwise the formation constitutes an apparent lithologic unit 
and appears as such on the maps; and it seems better to leave 
it as such instead of attempting to subdivide it at this juncture. 
If, however, it does consist of these two separate formations the 
necessity for the name largely disappears, and it is rather a pity 
that it was ever suggested. It is likely, however, to prove use¬ 
ful as a name for the considerable thickness of alternating beds 
of sandstone and magnesian limestone which everywhere im¬ 
mediately overlie the Potsdam sandstone in northern New York, 
and which should be mapped separately. 

There is then some reason to believe that there is present in 
this district a thickness of from 20 to 30 feet of limestone of 
lower Beekmantown age, quite like a similar thickness of rock 
at the summit of the Little Falls dolomite at Little Falls (where 
an unquestioned unconformity exists between the two), and hold¬ 
ing the same fauna. This is to be separated from the Little 
Falls dolomite under the name of the Tribes Hill limestone, and 
the same separation needs to be made in this district. The 
Theresa formation is to be restricted to the alternations of sand¬ 
stone and magnesian limestone which constitute the lower half 
of the formation as mapped. 

Age of the Potsdam and Theresa formations. These two 
formations, with a maximum thickness in this district of from 125 
to 150 feet only, represent the attenuated western edge of forma¬ 
tions which, in the Champlain valley, have tenfold that thickness. 
Their distribution shows that they were deposited in a subsid¬ 
ing trough along the present St Lawrence valley line, and that 
their deposit commenced at the east and worked westward. 
Everywhere along this line we find a sandstone beneath, grading 
upward into an overlying dolomite, and everywhere the horizon 
is characterized by the presence of the fossil Lingulepis 
acuminata. Everywhere along this line too there seems to 
be a break between these formations and the next formation 
above. The two formations seem then to be indissolubly bound 
together, to rest unconformably on the Precambric, and to be 
separated by an unconformity from the overlying formation. 
Since the formations are thin in the immediate district, and are 
thinning to the west and south, it follows that we are here in the 
vicinity of the western edge of the subsiding trough. Just how 
far west its deposits extended can not be told. According to 


GEOLOGY OF THOUSAND ISLANDS REGION 


67 


Ells the Theresa formation outcrops on Howe island, and on the 
Canadian mainland to a point midway between Gananoque and 
Kingston. 3 In the district about Kingston, as seen by us in 
1908 under Dr Ami’s guidance, the Potsdam is certainly present, 
though no Theresa was seen. The Potsdam is in patchy distri¬ 
bution, in depressions of the old Precambric surface, and is still 
thinner than it is at Clayton. The Theresa may never have 
been deposited here, or it may have been thinly laid down and 
then eroded, prior to Pamelia deposition. But it certainly seems 
as if, here at Kingston, we are very near the westerly end of this 
old, St Lawrence, Upper Cambric trough. 

On the basis of its fauna and position the Potsdam sandstone 
of northern New York was classified as of Upper Cambric age by 
Walcott, and in this he has been followed by practically all 
geologists. One can start on the formation at Lake Champlain 
and follow it without a break to Clayton, as a single continuous 
sandstone formation. Unquestionably its deposition commenced 
first at the east, and gradually extended westward; unquestion¬ 
ably the basal portion in the western sections is younger than the 
base in the east. But, so far as known to us, there is not a scrap 
of evidence to show that the deposition of sand had ceased, and 
that of dolomite begun on the east, before sand deposit had 
even commenced on the west. And even were this true, as is 
quite possible, there is certainly no evidence of such considerable 
age difference between the eastern and western ends of the 
formation, as to warrant their classification in two entirely dif¬ 
ferent geologic periods, the one end Cambric, the other Ordovicic, 
as has been recently done by Professor Grabau, who classes the 
Potsdam here as of Beekmantown age. 1 2 That seems to us a 
stretching of facts to fit theory that is certainly not permissible. 
It is quite possibly true that the sandstone deposition slowly 
worked its way westward by progressive overlap, as the trough 
continued to subside; but the evidence seems to us to indicate 
clearly that the length of time consumed in the process is far less 
than Grabau would have us believe. We have now gathered 
evidence from many points in New York indicating that every¬ 
where the Beekmantown formation is unconformable on what 
lies beneath. Detailed study of section after section has shown 
the presence of the unconformity in every case; and though the 

1 Roy. Soc. Can. Trans., ser. 2 , v. 9, § 4, p. 97-108. 

2 Science, n. s. 29 1356-58. 


3 


\ . 



68 


NEW YORK STATE MUSEUM 


work is only begun we are strong in our belief that uplift of the 
whole region preceded the Beekmantown. 

The type locality of the formation, at Potsdam, is precisely 
midway between Clayton and Lake Champlain. If one of these 
ends is of Potsdam, and the other of Beekmantown age, it is of 
interest to conjecture what the age may be at the type locality. 

To the writer it has long seemed clear that the sandstone and 
the overlying-dolomite must be classed in the same period, not 
only here on the west but everywhere in northern New York. 
By the overlying dolomite is meant not the true Beekmantown 
formation, but the dolomites which underlie this and which, the 
evidence indicates, underlie it everywhere unconformably. These 
dolomites have heretofore been classed with the Beekmantown 
and constitute Brainard and Seely’s “ Division A” of that forma¬ 
tion in the Champlain valley, with the underlying “ passage 
beds.” But while the beds of this division grade downward into 
the Potsdam they are separated by an unconformity from the 
beds of “ Division B ” just above, as recently shown by Ulrich; be¬ 
cause of which the writer has recently argued .that, since this 
unconformity is everywhere present in New York, marking the 
emergence of the entire region, it forms the logical plane of 
division between the Ordovicic and the group beneath. If this 
contention be well founded, the Potsdam and Theresa formations, 
the Little Falls dolomite, and “ Division A,” fall into the upper 
Cambric group of present classifications. Ulrich has, however, 
recently proposed a different classification, involving the in¬ 
sertion of a new group of period rank between the Cambric and 
Ordovicic, for which he proposes the name “ Ozarkic,” and into 
which the Potsdam and Theresa formations would fall. For 
many reasons the writer is in accord with this suggested innovation. 

« 

Pamelia formation 

In our district here the Theresa formation is everywhere over¬ 
laid by the limestone group here called the Pamelia formation. 
This is in some respects the most interesting formation in the 
section since it represents the thinned, shoreward edge of a 
formation which, while widepread elsewhere, has not hereto¬ 
fore been recognized in New York, and is in existence as a sur¬ 
face formation in the State only in this immediate area. Be¬ 
cause of its wide separation from other areas where the forma¬ 
tion appears, and because it represents only a local facies of the 


GEOLOGY OF THOUSAND ISLANDS REGION 


69 


mere upper part of the whole, the giving of a local name seems 
justified, and in Pamelia township the entire thickness is exposed. 
As has been shown there is plain evidence of an erosion interval 
between this and the Theresa, indicative of uplift to above sea 
level and of erosion on this land surface. As will be later shown 
this is an important and widespread break. The comparatively 
slight amount of erosion is indicative of low altitude for this land 
surface. 

1 he renewed depression which initiated Pamelia deposition 
came in from the southwest instead of from the east, involving 
change in the direction of slope of the surface. 

The formation consists essentially of limestone, though much 
of it is not pure limestone. It is conveniently separable into 
lower and upper divisions which differ in lithologic character. 
The lower division has always a sandy base, followed by alterna¬ 
tions of black limestone, blue limestone and gray (somewhat 
magnesian) limestone, often with shaly partings between the 
beds. The upper division contains much whitish, earthy lime¬ 
stone, with interbedded dove limestone and gray magnesian 
limestone. The black limestone characterizes the lower, and the 
earthy and dove limestones the upper division. 

In the western portion of the Theresa quadrangle the forma¬ 
tion has a thickness of 150 feet or more. Traced eastward 
across the quadrangle it thins considerably, and on the eastern 
margin appears to have less than half this thickness though here 
the drift is so heavy, and exposures so poor, that no good 
measurements can be obtained. However, 60 feet seems a generous 
allowance for the thickness here, and it is the beds of the lower 
division which have disappeared. 

Following the formation westward, across the Clayton quad¬ 
rangle to its disappearance beneath the river, the belt of outcrop 
swerves somewhat to the north, and the formation thins somewhat 
in this direction also. If it could be followed due west across the 
quadrangle it would no doubt hold its thickness or even perhaps 
increase. It is the northward shift that causes the thinning. A thick¬ 
ness of at least 80 feet is maintained to the river however, and the 
formation passes across into Canada with this amount not materially 
reduced. The shore lines of this depositional basin then lay not far 
distant to the east and north of the district and the invasion of the 
sea must have come from the opposite direction. 

In the immediate district the formation rests everywhere on the 
sandy dolomites of the Theresa. In the district about Kingston it 


70 


NEW YORK STATE MUSEUM 


rests either on the Potsdam or on the Precambric. In the upper 
Black river valley it lies on the Precambric. All these formations 
are capable of furnishing sandy material and hence the sandstone 
base of the formation is but natural. The Theresa, however, is less 
capable in this respect than are the other formations,, thus account¬ 
ing for the fact that this sandy base is a less prominent feature of 
our area here than it is in the others. 

Hereabout, the best section of this basal material seen is at the 
foot of the Pamelia inface, 2 miles east of Perch lake, Theresa 
sheet. The small creek there runs over a massive, bared layer of 
Theresa dolomite, above which a 14 inch layer of the same shows in 
the bank. Above this lie weak, greenish sands and sandy shales, 
with an exposed thickness of some yV 2 feet, the basal layer some¬ 
what pebbly and more massive than the remainder. The cement is 
calcareous and abundant. The rock is therefore weak and seldom 
exposed, yet in a sufficient number of places, and sufficiently well 
to show that it everywhere underlies the limestone throughout the 
district with a thickness of from 10 to 15 feet, much of which is 
shaly. It is a more calcareous, and vastly weaker rock than even 
the most calcareous beds of the Potsdam, and quite different from 
it lithologically; so unlike in fact that the two rocks can be readily 
distinguished from one another by lithologic character alone through¬ 
out the whole region. This becomes of importance in the region 
around Kingston, where in our opinion both sandstones are pres¬ 
ent but without the separating Theresa formation. The Pamelia 
basal sandstone rests, now on the Potsdam and now on the Pre¬ 
cambric, is less shaly and attains greater thickness than on the 
New York side, and shows at times astonishingly coarse basal 
conglomerate. In its green color, weathering to a red mottling, 
in its abundant calcareous cement, and in its weakness, it corre¬ 
sponds exactly with the New York rock, while the silicious Pots¬ 
dam beneath also corresponds with the Potsdam across the river in 
every minute lithologic detail, even in the “ tree ” concretions. 

In the upper Black river valley both Potsdam and Theresa are 
absent and the Pamelia rests on the Precambric. At Martinsburg 
the wonderfully complete section shows a thickness of 19 feet for 
the basal sandy portion, weak green sandstone, blotched with red, 
abundant calcareous cement and with thin conglomerate at the base. 

Where thickest, the limestones of the lower division show, above 
the basal sandstones, beds of gray, magnesian limestone with fre¬ 
quent shale partings; these are followed upward by black, fos- 
siliferous limestones, holding a rather abundant marine fauna; then 






GEOLOGY OF THOUSAND ISLANDS REGION 


7 1 


succeed alternations of blue limestone and gray, magnesian lime¬ 
stone, with occasional white, earthy beds, and with thin recur¬ 
rences of the blackish limestones with traces of the marine fauna; 
in the other beds the fossils are chiefly, or exclusively, ostracods. 
As the formation thins to the east and west the lower gray beds 
disappear, bringing the basal sands up under the black limestone i 
with further thinning this disappears in its turn, but at the same 
time the higher black layers seem to show increased thickness and 
prominence, so that where the lower division has been thinned to 
a few feet, as it has over much of the region, it is still character¬ 
ized by black, fossiliferous limestone. 

This lower division has a measured thickness of 70 feet in a 
nearly complete section by Perch lake. It is likely somewhat 
thicker to the west but probably does not exceed this more than 
15 or 20 feet. A well near Stone Mills was drilled 125 feet in 
the formation without reaching the base, but drilling commenced 
in the upper division and how large a part of that is involved is 
not known, though likely 50 feet must be allotted to it. 

The upper division consists of alternations of white earthy lime¬ 
stone, and of dove limestone, with occasional beds of gray, and of 
blue, hard, subgranular or subcrystalline limestone; there is also 
some yellow, earthy limestone, and a horizon where a reddish tinge 
is likely to prevail. The summit is chiefly of dove limestone. The 
earthy limestones hold numerous nodules of coarsely crystalline 
calcite, which attain quite large size in some of the upper layers, 
with diameters of from 3 to 5 inches. Celestite nodules also occur, 
but much less frequently. Much of the upper division is thin 
bedded, weathering into small, yellow stained slabs an inch or two 
in thickness; and the stone walls of this thin material which line 
the roadsides and separate the fields everywhere characterize the 
upper Pamelia country. 

The surfaces of many of the layers are covered with shrinkage 
cracks, especially in the upper part of the division. Sand grains 
also appear in some of the white, earthy beds. Abundant Stylio- 
lites occur at certain horizons in the upper dove limestones. The 
evidence of estuarine, or lagoon deposition, with evaporating 
waters, occasional exposure of broad mud flats, and from time to 
time replenishment of the water from the sea outside, freshening 
it and bringing in traces of the outer marine fauna to mingle with 
the ostracod fauna of the lagoon, is very plain and conclusive; 
prevalence of somewhat arid climate is also suggested. The rock 
is very like, and the climatic and depositional conditions very simi- 


72 


NEW YORK STATE MUSEUM 


lar to those which prevailed during the formation of the Siluric 
waterlimes of central New York. 

The thickest measured section of the upper division, i mile 
southwest of Depauville, Clayton sheet, gave a thickness of 82 feet. 
The contact with the overlying Lowville was shown, and the base 
of the section can not have been greatly above the base of the upper 
division. Near the river west from Clayton a similar thickness was 
found, though the upper part of the section was considerably in¬ 
terrupted. In all probability the thickness does not vary greatly 
from this over the entire map limits, with the exception of the, 
eastern margin of the Theresa quadrangle. The thickness of the 
two divisions together then indicates a maximum of about 150 feet 
for the formation hereabout. 

The fauna of the formation consists chiefly of ostracods, which 
are found at all horizons, and Ulrich remarks on the absence in 
the formation of certain large sized species of Leperditia and 
Isochilina which occur in the Lowville above. The marine fauna 
of the lower division includes gastropods, cephalopods, lamelli- 
branchs, trilobites, corals and sponges. The most abundant and 
characteristic form is the coral Tetradium syringopo- 
r o i d e s , which abounds in certain layers of the black limestone. 
The most common trilobite is a species of Bathyurus which is very 
like the common Bathyurus e x t a n s of the Lowville, but 
which Ulrich distinguishes as a different and unnamed species, 
which is a common Stones River form. Among the gastropods he 
identifies Lophospira perangulata, another Lophospira, 
and a Helicotoma. The fauna as a whole is quite similar to that 
of the Lowville, though the differences are characteristic. 

Since the formation is a new one to the State the publication of a 
few detailed sections is advisable. The best continuous section of 
the lower division is found in the bed of a small creek which tumbles 
down the steep bluff face east of Perch lake (Theresa sheet), cutting 
the 400 foot contour where the figure 400 appears on the map. 

6' White, earthy limestone in thin beds, often shaly looking 

3' 6" Brittle, tough, blue to blue black limestone, thick bedded 

1' V2" Gray, subgranular, magnesian limestone, weathering white 
1' 5" Massive bed of blue, subcrystalline limestone 

1' 3" Massive bed of gray, magnesian limestone 

5" Blue, subcrystalline limestone 
1' 8" Gray, magnesian limestone, two layers 

1' Concealed 

3' Finely laminated gray to blue gray, magnesian limestone, fine-line 

weathering on edges 

io' Concealed 

10' 3"' Black to blue black, fossiliferous limestone, upper 3 feet thin 
bedded, remainder fairly massive 


Plate 16 



Exposure i *4 miles east of Perch lake, of limestones of the lower division 
of the Pamelia formation; about 6 feet of black, fossiliferous limestone 
above and twice that thickness of gray, magnesian limestones beneath. 
H. P. Cushing, photo, 1907 

























GEOLOGY OF THOUSAND ISLANDS REGION 


73 


8' Gray magnesian limestone, weathering whitish, fairly massive be¬ 

low, upper 2 to 3 feet thin bedded and earthy 
i' 6" Curdled looking intergrowth of blue limestone and gray, mag¬ 
nesian limestone, the former weathering most rapidly with pro¬ 
duction of fantastic weathered surface 
19' Alternating, gray, earthy, impure magnesian limestones, and thin, 

shaly looking partings, limestone weathering at times to a green¬ 
ish tinge, at other times whitish 
2' Greenish to olive, calcareous shale’ 

2' Greenish, calcareous sandstone, coarse, well rounded sand grains 

set in calcite paste 


72' 3/2" 

The lower 4 feet of the section belong with the basal, sandy por¬ 
tion of the formation, without any question, so that the actual 
base is nearly reached. Above is a thickness of 28 feet of im¬ 
pure, magnesian limestone before reaching the base of the fos- 
siliferous black limestone, the most characteristic member of the 
lower division. Plate 16 is a photograph of beds of this hori¬ 
zon exposed in the creek bed just north of the road i]A, miles east 
of Perch lake. In the section here 14 feet only of gray magnesian 
beds are found underneath the black limestone, as against the 28 
feet of the Perch lake section. A mile further east these have dis¬ 
appeared letting the black limestone down on the basal sand beds, or 
rather bringing them up to it. 

Judging from other sections the concealed 10 feet of the section 
is occupied by weak, earthy, thin bedded, whitish limestone, and 
the section would be capped by a very massive, blue, subcrystalline 
limestone which forms a strong shelf 'everywhere through the 
district. 

The best sections of the upper division are all on the Clayton 
quadrangle. One measured up the bed of the small creek which 
tumbles down the bluff into the Chaumont river a mile southwest of 
Depauville is as follows: 

1' 8" Brittle, light gray, subcrystalline limestone 
16' 1" Thin bedded, brittle limestone, mostly dove, but with beds of 
grayer limestone 

T Massive layer of dove limestone 

10' 8" Irregularly bedded, gray to white, earthy limestone, mostly thick 
bedded ; midway is somewhat sandy 
5' Thick bedded, uneven, gray limestone 

3' Thin bedded dove limestone in 3" to 6" layers 

4' 2" Gray white, earthy, irregular limestone, both thick and thin beds 
5' 4" Dark and light gray, brittle, subcrystalline limestone 
1' 8" Gray white, impure, earthy limestone 
T 8" Brittle, blue gray, subsrranular limestone 
5' 10" Impure, earthy, white limestone., irregularly bedded 
1' Hard, blue gray, subcrystalline limestone 




74 


NEW YORK STATE MUSEUM 


The section terminates downward 20 feet above the river level. 
Above, after a 10 foot gap, come 15 feet of thick and thin bedded, 
dove limestone, often mud cracked, and then the Lowville base, 
giving an 80 foot thickness to the section: It is not certain whether 
its base overlaps the summit of the previous section of the lower 
division or not, though it is thought not. But the uppermost 6 feet 
of that section belong to the upper division and the thickness is 
nearly the same as that of the impure, earthy limestone at the base 
of this section. Even granting that amount of overlap, the two 
sections taken together give a certain thickness of 150 feet to the 
formation and this may need to be increased by from 10 to 20 feet. 

Another most excellent section is that given in a quarry up the 
river bluff 4 miles west of Clayton [pi. 17]. A slightly general¬ 
ized statement of it will serve the purpose here. 

1' 8" Thin bedded, dove limestone 

5' 6" Gray white, 'impure earthy limestone, mostly thin bedded, some 

thick and irregular beds 

7' 5" Rather massive limestone beds averaging 20" in thickness, gray in 

color, in part earthy, in part subcrystalline 
2' 9" Dove limestone, three beds, the lower thick, the two upper thin 
3' Hard, gray, subcrystalline limestone, two thick beds with a thin 

shaly parting between 
i' 5" Dove limestone, two beds 
T 8" Hard, gray limestone, upper inch is shale 
1' 8" A hard, dove limestone layer 
1' Gray white, earthy limestone, thin bedded 

2' g" Brittle, gray, subcrystalline limestone 
1' 8" Massive, dove limestone bed 

iT* Thin bedded, whitish, earthy limestone 
1' Gray, subcrystalline limestone, slight pinkish tinge 

7' 1" Gray, earthy limestone in thick beds with shaly partings; a thin 

dove layer near the top; reddish tinge at times 
g' 6" Blackish limestone, upp’er bed very massive 

49 ' 


The black limestone at the base of the section seemed to the 
writer to smack strongly of the lower division, though the marine 
fauna was but feebly developed, and Ulrich expressed doubts in 
the matter. Certainly beds of the type are not usually found in the 
upper division. A short distance back from the river another 
quarry shows a thickness of 15 feet of the succeeding beds, the entire 
thickness being of dove limestone, both thick and thin beds, with 
sparing fossils. Further back, by the roadside is a shallow quarry 
exposing 4 feet of still higher beds, two massive* dove layers with 
similar but thinner beds between, the thick beds holding Phytopsis. 
Such beds elsewhere mark the 'extreme summit of the Pamelia. 
Were the upper part of the section complete there would be shown 
here a thickness of more than 80 feet belonging to the formation. 



Plate 17 




Quarry in the upper Pamelia formation, by the river 4 miles west of 
Clayton; alternating beds of dove limestone, and whitish, earthy lime¬ 
stone The upper view is a somewhat more distant one showing a greater 
thickness of the upper beds. Photo (upper) by H. M. Ami and (lower) 
by E. O. Ulrich, 1908 












Plate 18 



Upper view. Dove colored limestone beds of extreme upper portion of 
Pamelia formation in railroad cut just south of Sanford Corners. Theresa 
quadrangle, looking east. 

Lower view. Contact of Pamelia and Lowville formations at the south 
end of the railroad cut. E. O. Ulrich, photo, 1908 











/ 












GEOLOGY OF THOUSAND ISLANDS REGION 


75 


Both these sections are imperfect in their showing of the beds 
of the extreme summit. The most excellent section shown in the 
railway cuts just south of Sanford Corners (southeastern part of 
Theresa quadrangle) supplies this deficiency [pi. 18]. 

I 4 Two 8' layers of blue gray, crystalline limestone, abundant lamelli- 
, branch casts full of crystalline calcite; dove limestone mud balls 

i Mud cracked, argillaceous, somewhat granular, bluish limestone, 

weathering yellowish 

i Thin bedded, blue, granular limestone, conglomeratic, quite shaly 

below, very fossiliferous, chiefly bryozoa; base of Lowville 
ii" Dove gray, line, impure limestone, weathering light 
3' 2" Laminated, mud cracked, gray dove, argillaceous limestone, thin 
bedded, ripple-marked, worm-burrowed 
1 9 // A 6" layer below and an upper 15" bed; fine dove limestone with 

calcite spots, gastropods and cephalopods 
T 10" Gray, granular limestone, crystalline specks and spots; shaly 
below, more massive above 

5 / 6" Finely granular, blue dove limestone, shaly below, more solid 

above; blocky weathering; calcite seams and spots; sparse 
Phytopsis in upper part 

4' 6" Mottled, blue dove limestone, thin bedded above and below; 

much crystalline calcite replacing poorly preserved fossils 
8" Blue black, finely granular, dove limestone; calcite spots 
r' 10" Blue gray, calcareous, sandy shales, weathering yellowish 

7" Dark blue, finely crystalline limestone; conglomeratic 

8" Blue gray, calcareous shales, weathering yellowish; sand grains 

8" Blue dove limestone; base weathering sandy looking 

9" Sandy, argillaceous, shaly limestone, weathering yellowish 
9" Blue dove, mottled limestone 

3' 1" Gray blue, dove limestone, somewhat muddy, shaly fracture 

7" Blue dove limestone, small limestone pebbles 
1' 9" Solid layer of blue dove limestone, rudely laminated with or¬ 
ganic streaks 

T 10" Laminated, argillaceous, fine grained, mottled, blue dove lime¬ 
stone ; two seams 

T 4" Fine, flinty, dove limestone; slightly conglomeratic at base 
1' 10" Fine, flinty, dove limestone, with a shaly streak of 3" ; lower 
portion with Phytopsis 

4 Rather compact, fine dove limestone; a little Phytopsis in the 

upper 3" 

T 2” Blue dove, thin and irregular bedded limestone 
2' 6" Measures concealed 

5" Blue dove, mottled, laminated limestone, small ostracods 
45 ’ 5” Of which the lower 41' 8" belongs to the Pamelia 

The 1 foot layer, third from the top of the section, is divisible into 
an upper 3 inch portion, full of fossils, making an irregular contact 
with the remainder, which lacks fossils, and in Ulrich’s judgment, 
with which we coincide, the line between the two formations is 
properly drawn at that slight break. These upper dove limestone 
layers, over 40 feet thick in this section, have puzzled us much and 
have been difficult to classify. They are above the white, earthy 
beds which are the most characteristic lithologic feature of the 
upper Pamelia, and while they are precisely like the dove limestones 



7 6 


NEW YORK STATE MUSEUM 


which are intercalated with these, they are also very like the Low- 
ville, with which we at first classified them. Their shift from the 
one to the other considerably diminishes the supposed thickness of 
the Lowville of the district and correspondingly increases the 
Pamelia. 

In this, cut, the first of three such along the railway south of San¬ 
ford Corners, the rock dip is to the south, carrying the Pamelia 
summit below the track level before reaching the second cut. The 
dip then reverses, becoming north, and bringing up the Pamelia 
again in the third cut. At the north end of this cut the basal, 
bryozoan, conglomerate layer of the Lowville has increased in thick¬ 
ness to 38 inches, as against a 3 inch thickness in the section just 
given, and immediately beneath it is a layer of exceedingly fine 
grained dove limestone mud, which is the exact counterpart of the 
material composing the conglomerate pebbles [pi. 31, lower figure]. 
This layer was wholly lacking also in the previous section. At 
the south end of the cut the Lowville shows 6 j 4 feet thickness of 
basal layers which did not appear in the section in the north cut, 
and there is also a thickness of full 6 feet of the pebble-furnishing, 
dove limestone at the Pamelia summit, which is also lacking in that 
section. The evidence of unconformity between the two forma¬ 
tions is clear, and found as Ulrich had predicted that it would be. 
The fact that both formations thicken together is, however, some¬ 
what unusual, and suggests that some of the warping shown occurred 
in the uplift following Pamelia deposition, its summit being pro¬ 
tected from wear in a shallow trough, in which also the first be¬ 
ginnings of Lowville deposition took place. 

The section here in the south cut is given on page 84 under the 
account of the Lowville formation. 

The section just described gives an excellent idea of the deposi- 
tional conditions which prevailed during the closing stages of 
Pamelia deposition. The fine limestone muds, much sun cracked, 
worm-burrowed, even ripple-marked; the injection of sand grains 
and the occurrence of the occasional limestone conglomerates, 
together with the abundance of ostracods and the general absence 
of marine forms; all these point unquestionably to intermittent de¬ 
position in a shallow lagoon, with drying mud flats produced from 
time to time, and with only occasional admission of sea water. 
Though the uppermost break, here chosen as marking the base of the 
Lowville, seems much the most considerable of all, the presence of 
more than one conglomerate horizon, of more than one horizon of 
sand grains, indicates several minor breaks in the summit of the 


GEOLOGY OF THOUSAND ISLANDS REGION 


77 


formation, and much complicates the successful working out of the 
section. 

Extent of the Pamelia formation. In a preliminary paper pub¬ 
lished some months ago, based on the field work up to the close of 
1907, the writer attempted to predict the extent of the Pamelia 
formation in New -York and adjacent Ontario, in so far as the 
published literature warranted. The result of the field work of 
1908 necessitates some modification of the statements there made, 
all of which prove to have been too moderate. 1 

The study of the formation on the Clayton sheet, and the work 
about Kingston, show that the formation does not thin as rapidly 
in those directions as had been supposed. About Kingston the 
formation has much prominence and considerable thickness, much 
of the upper division, and the basal sandstones being well repre¬ 
sented. i he upper dove limestones of the New York section are 
here capped 'by thin bedded, earthy, shaly layers, weathering yel¬ 
low, above which the Lowville comes in, with its basal conglom¬ 
erate. The division plane between the two formations is therefore 
much easier of recognition than on the New York side. 

L p the Black river valley we measured sections at Lowville and 
on Roaring creek, near Martinsburg, the latter a wonderfully fine, 
continuous section from the Precambric up into the Trenton. We 
were at the time ignorant of the fact that Prof. W. J. Miller was 
engaged in the areal mapping of the Port Leyden sheet, on which 
this section occurs. That being the case its detailed exposition is 
left for him. 2 Suffice it to state that it shows a thickness of 72 
feet, 6 inches of Pamelia, overlaid by 54 feet, 7 inches of Lowville; 
and that, of the Pamelia, the lower 19 feet is of sandy beds, fol¬ 
lowed by 8 feet of blackish limestone with abundant marine fossils, 
the remainder showing alternating beds with the characters of the 
upper division though the upper dove beds are lacking. Miller 
reports that the formation is traceable to the south line of the Port 
Leyden sheet, but does not appear beyond. This is, however, well 
toward the upper end of the Black river valley, and gives the 
formation in New York a measured length of outcrop of 70 miles, 
from southeast to northwest. The Kingston occurrence adds 15 
miles more to this distance, and it is quite probable that the forma¬ 
tion may run west for some miles across the Ontarian peninsula. 

Our work was done, and a preliminary paper published, while in 
ignorance of the existence of a paper by Dr Ells upon the adjacent 
Canadian district. This paper, as the quotation which follows will 


1 Geol. Soc. Am. Bui. 19:165-71. 

2 N. Y. State Mus. Bui. 135, p. 22, 23. 



78 


NEW YORK STATE MUSEUM 


show, distinctly recognizes the chief physical oscillation of the 
region. 

It would, therefore, appear that some marked but well defined 
change of level occurred in the area south of the Kingston-Brock- 
ville Archaean axis at the close of the Potsdam, which was also 
materially reduced in thickness. This is in marked contrast to the 
conditions which prevailed north of that axis throughout the Ottawa 
basin; and it may be supposed that, at a certain stage in the de¬ 
position of the sandstone formation, the surface was raised above 
the level of the sea, and so remained till the beginning of Black 
River time throughout the whole extent of Lake Ontario. 1 

Age of the Pamelia formation. Our section here shows the 
Pamelia formation to lie between the Theresa and Lowville forma¬ 
tions, separated from each by an unconformity, the lower of which 
is much more important than the upper. In the Champlain valley 
two great formations, the Beekmantown and the Chazy, with a 
combined thickness of 2000 feet, occupy this same interval, yet the 
Pamelia formation is unlike either. On the basis of its position 
and fauna, Ulrich correlates it with the upper part of the Stones 
River formation, a formation of Chazy age, but laid down in a 
separate basin from the Chazy, so that faunally and lithologically 
the two are quite distinct. The Stones River basin lay to the west 
and southwest of the Chazy trough, and was much larger. The 
barrier between the two in New York comprised the Mohawk val¬ 
ley region, much of the Adirondack district, and at least the west¬ 
erly portion of the St Lawrence trough. 2 

Curiously too, although much sedimentation occurred in the 
Champlain trough during Beekmantown-Chazy time, and only 
Pamelia deposit in our district here, yet this is practically un- 

1 Roy. Soc. Can. Trans, ser. 2, v. 9, § iv, p. 106. 

It is to be noted that Black River is here used in a general sense as 
including the whole body of limestone. 

2 Since the above was written another paper by Professor Grabau has 
appeared which presents more definitely his interpretation of the rock suc¬ 
cession and age in this district [Jour. Geol. 17:211-26]. The fundamental 
difference between us seems to be that he regards the break between the 
Theresa, and Pamelia formations as representing the somewhat expanded 
westward continuation of the break in the Champlain valley between the 
Beekmantown and Chazy, and recognizes no break there between the Cam¬ 
bric and Beekmantown. We regard it as representing most of Beekman¬ 
town and all of lower and middle Chazy time and think that, to the east 
in the St Lawrence valley, it splits into two breaks with a wedge of later 
Beekmantown inserted between. He thinks there is no Cambric here, and 
that the Potsdam and Theresa are of Beekmantown age; and he recog¬ 
nizes no break between the Cambric and Ordovicic. We find evidence of 
a considerable series of oscillations of level in the general region, while he 
argues, if we correctly understand him, for a slow, progressive subsidence 
of the region during Potsdam and Beekmantown time. 



GEOLOGY OF THOUSAND ISLANDS REGION 79 

represented in the Champlain area, Ulrich correlating the dove, 
reef limestone, only a few feet in thickness, which forms the 
basal member of the upper Chazy there, with the Pamelia hori¬ 
zon. In the much more complete sections about Chambersburg, 
Pa., a 200 foot thickness of limestone with an upper Chazy fauna, 
separates the Pamelia horizon from the Lowville. Subsidence 
apparently ceased in the Champlain basin during the time of 
Pamelia depression and deposit in this district, and as this ceased 
here, upper Chazy depression was renewed there, the uncon¬ 
formity between the Pamelia and Lowville representing this 
upper Chazy interval. Knowledge of this led Ulrich to predict 
the unconformity and induced the search for it. Otherwise it 
might easily have escaped our notice. 

Mohawkian series 1 

The Mohawkian series comprises the Black River and Trenton 
groups. The Black River group is composed of the Lowville beds 
including the Leray limestone, and the Watertown limestone. In 
giving to the Black River group this larger scope, we return to the 
original conception of several of the geologists of the First Geo¬ 
logical Survey of New York, i. e. Hall, Vanuxem and Mather, with 
the exception that the Black River then also included the Chazy 
limestone. Emmons, however, to whose district the Black River 
region belonged, did not use the term “ Black River.” He dis¬ 
tinguished the “ Birdseye limestone ” and the “ Isle La Motte 
marble ” employing the latter term for a bed locally the main 
object of the quarrying industry, and known as the “ Seven foot 
tier.” Hall, in the first volume of the Palaeontology of New York, 
restricted the term Black River to this “ Seven foot tier ” and 
through his influence and the description of a very striking 
cephalopod fauna from the bed, the term “Black River” was 
quite generally accepted for the “ Seven foot tier.” Since, how¬ 
ever, mainly through the investigations of Dr Ulrich, the fact has 
become apparent that beds which in the Mohawk valley and the 
Lake Champlain region have been referred to the Black River 
limestone, are both older and younger than the Black River as re¬ 
stricted by Hall, but fall within the limits of the original concep¬ 
tion of Black River, it has become advisable to revive this original 
usage of the term to avoid confusion. The “ Seven foot tier ” or 
Black River limestone of Hall has then to be renamed and the term 
“Watertown” is here used for this formation [see p. 841 . 


1 By R. Ruedemann. 



8o 


NEW YORK STATE MUSEUM 


Lowville limestone. The Lowville limestone which is the 
“ Birdseye limestone ” of the old Geological Survey reports has 
its maximum development in New York in the region of the 
lower Black river, or in the southern portion of the area here 
mapped. It reaches there about 60 feet in thickness. It consists 
typically of thick and thin bedded, fine grained dove limestone 
which shows a characteristic ashen gray weathering and con¬ 
tains either numerous more or less vertical worm tubes denoted 
as Phytopsis and filled with calcite (producing the “ birdseyes ” 
in sections) or shows in profusion the horizontally spreading 
tabulate coral Tetradium cellulosum and related 
species. Between these typical Lowville beds there are inter¬ 
calated others of subcrystalline dark to black limestone, or of 
oolitic or also of shaly whitish weathering limestone. These inter¬ 
calations usually contain a larger fauna than the dove limestone 
and carry lamellibranchs, gastropods and cephalopods, as well 
as ostracods and trilobites. 

The basal bed is conglomeratic and of very variable thickness; 
it is overlain by several feet of strata that contain quartz grains 
or grit bands and are more or less shaly, the shaly limestone 
gradually becoming more massive upward and assuming the 
characters of the typical rock. These more or less sandy beds 
comprise about 4 feet. 

The uppermost portion of the Lowville beds which has been 
mentioned by the earlier authors as the “ cherty beds ” has been 
found by Professor Cushing and the writer to be quite distinct 
from the typical Lowville beds and separated from them by an un¬ 
conformity. It has for that reason been here distinguished as a 
subdivision under the name Leray limestone and will be described 
separately [see below]. 

It appears that in this region the Lowville beds beneath the Leray 
member can be conveniently divided into an upper and lower divi¬ 
sion of nearly equal thickness, the upper division alone containing 
the abundant Tetradium cellulosum and larger Phytop¬ 
sis, as well as the typical massive dove limestone strata, while in 
the lower division more dark or black subscrystalline limestones 
containing only smaller forms of Tetradium and Phytopsis and 
more thin bedded dove limestones abound. 

In this lower division also two or more horizons of Stromato- 
cerium can be observed, which give the beds a very irregular con¬ 
cretionary appearance. These horizons are well seen in the rail¬ 
road cut just south of Sanford Center, also where the road crosses 


GEOLOGY OF THOUSAND ISLANDS REGION 8 1 

the southern branch of Horse creek on the Clayton quadrangle 
and best along the Black river just east of the boundary of the 
map. Such beds are seen in the lower third of the exposure on 
plate 19; other bunchy surfaced layers also appear, with the 
depressions filled in with shaly material, which seem clearly due 
to rill action on tide flats. 

While the sand grains which are found in greater or smaller 
number floating in the basal limestones indicate, if we may 
follow recent investigations, the conditions of quiet embayments, 
in which sands washed in from the land, drifted out into the bay 
and gradually sank to the bottom, becoming imbedded in the 
limestone mud, the following beds indicate that this sea became 
gradually deepened. The lower division still exhibits in the 
shaly beds the sun cracks and ripple-marks and numerous mud 
balls characteristic of mud flats while the upper beds in their 
more uniform, massive character contain the criteria of deposi¬ 
tion farther off the coast line. It follows thence that the Low- 
ville sea was an advancing sea in the area here mapped. From 
the development of the Lowville in the Mohawk valley and north 
of the Adirondacks, it can be inferred that this transgression took 
place from the southwest. In the Mohawk valley the distribution 
of the Lowville is very erratic, as fully discussed by Cushing in a 
former paper [Geology of the Northern Adirondack Region], it 
being entirely absent in some localities while in others it is con¬ 
nected by so called passage beds with the underlying Beekmantown. 
This erratic distribution is then clearly due to the irregularity of 
tlie surface over which the sea advanced, the Mohawk valley inter¬ 
secting the deeply indented coast line of the Adirondack peninsula 
in Lowville time. In the Champlain basin at the base of the Black 
River group an outcrop of typical Lowville rock occurs in the Crown 
Point section. The bed referred to consists of 5 feet of dove lime¬ 
stone with Phytopsis tubes but otherwise apparently unfossiliferous. 
However, 12 feet above this dove limestone the writer found 
a large colony of Tetradium c e 11 u 1 o s u m together with 
Orthoceras recticameratum, another typical Low¬ 
ville fossil, thereby clearly demonstrating the presence of the Low¬ 
ville fauna in the Champlain basin. 

Four species of fossils have to be considered as highly charac¬ 
teristic of the Lowville formation in the area here mapped, viz; 

Tetradium cellulosum (Hall) 

Orthoceras multicameratum (Emmons) Hall 
O. recticameratum Hall 
Bathyurus extans (Hall) 


82 


NEW YORK STATE MUSEUM 


These species are not known to occur above or below the Low- 
ville limestone, and are common enough to occur in every exposure 
of the formation. 

Tetradium cellulosum forms large colonies, attain¬ 
ing sometimes a diameter of several feet (specimens of this size 
collected by the writer along Black river) and consisting of fre¬ 
quently dividing branches that radiate horizontally and obliquely 
upward from a common center. Its most characteristic aspect, 
however, is seen on sections where the squarish cells with their 
fission septa produce a neat lattice pattern. Different, hitherto 
undescribed species with looser arrangement of the polyparies or 
cells, occur in lower horizons. 

Both Orthoceras multicam eratum and O. 
recticameratum are easily recognized by the close ar¬ 
rangement of their septa and the latter form possesses in the 
angular course of the septa a character not shown by other 
species. 

Bathyurus extans apparently occurs throughout the 
formation but is most frequent in several bands. It is, as Dr 
Ulrich informs us, preceded by closely related and very similar 
prenuncial forms in the Pamelia formation. 

On account of the but slight difference in the compactness of 
the rocks between the Lowville and Pamelia formations, the 
former is not set off by an escarpment from the other, but both 
form one continuous plateau. In some districts the lower Low¬ 
ville contains easily worked layers, furnishing subcubical blocks 
and the composition of the fences of such blocks is a quite char¬ 
acteristic aspect for this horizon. 

Since the formation received its name from Lowville and a 
section of this type locality has not yet been furnished, we insert 
here the section, obtained at this place in the quarry at the railroad 
bridge over Mill creek, where in the creek bank the uppermost 
part of the Pamelia (about 12 feet) is shown and a continuous 
section into the Leray limestone can be obtained. On account of the 
nearness of Lowville to the area here mapped, the Lowville section 
is to be considered as typical also for this area. For comparison 
we add the section measured in the Sanford cut which contains 
about three fourths of the formation. Another fine section was 
observed in the bank of the Black river above Watertown, opposite 
the filter plant, just outside the map limits, and a section of about 
56 feet from the 7 foot tier downward is exposed in the high river 
bank opposite the Ontario Paper mill, 2 miles east of Brownville. 






GEOLOGY OF THOUSAND ISLANDS REGION 


83 


Unfortunately no good sections were found in the northwestern 
portion of the area, permitting a comparison with that of Lowville 
as to thickness and arrangement of horizons. 


Section at railroad bridge at Lowville (type section) 
Lowville section 

6 Cherty beds. Dark blue, finely granular limestone, dirty white 

f tt weathering. Columnaria horizon at base 
1 1 6" Bed full of horizontal worm tubes. Chert horizon at base 
5 9 1 ransitional bed from Leray to typical Lowville. In aspect like 

cherty beds with a few cherts, but contains also Tetradium 
cellulosum, besides Leperditfa fabulites, 
Rafinesquina minnesotensis, and other brachiopods 
and bryozoans 
Base of Leray 

3 ' Dove limestone, massive. Phytopsis tubulosum com¬ 

mon near top; a few Tetradium cells 
3' 1" Compact dark dove limestone, full of fossils (Tetradium, gastro¬ 

pods, lamellibranchs) and of crystalline calcite 
4' 9" Thin bedded, dove limestone, full of Tetradiums (form with nar¬ 
row, round tubes) 

5" Dark, fine grained impure limestone with argillaceous streaks, 
containing a small Mont-iculipora 

2' 4" Lighter, massive bed of dove limestone with few Tetradiums. 

Lowest 8 inches black, with thin seams of flint 
4"- 7" Stratum of granular,. light gray limestone full of lamellibranchs 
and gastropods, their shells filled with calcite 
i' 3 " Black, massive, crystalline limestone, full of Tetradium 
3' 4" Black to dark gray thin bedded dove limestone, containing a few 
Phytopsis 

4" Same rock as above, but full of a narrow form of Phytopsis 

4" Black, dove limestone stratum full of crystalline calcite 
T 7" Dark gray, granular limestone with many calcite crystals. Bottom 
of quarry 

4' Dark gray, thin bedded, dove limestone, weathering shaly 

4' Harder, argillaceous limestone 

3' 10" Shaly dove limestone, varies much, very shaly in middle, full of 
sand grains, contains a few lamellibranchs 
T Hard, oolitic blue limestone, full of quartz grains and pebbles 

6"-io" Shaly bed with seams of quartz grains or grit bands 
o- 3'+Dark bluish gray limestone, full of pebbles, shale below. Very 
variable in thickness. Unconformity. Base of Lowville 
1' 10" Gray and pinkish granular limestone, dove in parts 

4" Thin bedded, shaly limestone, sand grains near top 
1' 10" Dove, dark mottled, fine grained limestone, typical upper Pamelia 
T 7" Dove limestone with argillaceous reticulation, light pink in parts, 
weathering shaly 

9" Bluish black flinty dove limestone 

10" Gray, granular limestone with calcite and quartz grains, in parts 
conglomeratic, a few fossils. (Rafinesquina incras- 
s a t a ) 

T 5" Light dove limestone, somewhat argillaceous, coarsely laminated. 
Phytopsis on top 

2' Grayish, bluish, blocky, subgranular limestone 

1' Compact bed of harder, light bluish gray limestone 

i'+ Dove, light gray limestone with crystalline specks 


8 4 


NEW YORK STATE MUSEUM 


Sanford cut section 

27' 2" Lowville 

1' 4" Blue gray, oolitic limestone, full of lamellibranchs and with 
Tetradium c e 1 1 u 1 o s u m 

6' Massive Tetradium beds, dove limestone full of crystalline calcite 

5' Thin bedded, blocky dove limestone; second zone of Bath- 

yurus extans 

4' Irregular, thin bedded, blocky, dove limestone, more massive above, 

culminating in a heavy, irregularly surfaced Stromatocerium 
layer; holds B . extans below 

22"-i4" Thin bedded, fossiliferous, dove limestone, with Camarotoe- 
c h i a plena, fitting to uneven surface beneath 
i 6"-24" Heavy, massive dove limestone, Tetradium and other fossils, 
masses of Stromatocerium at surface, giving bunchy character 
4' 6 " Speckly dove limestone with shaly seams; bryozoa, Tetra¬ 
dium syringoporoides (Ulrich, ms) and other fossils 
3' 2" Heavy, massive bed of gray, crystalline limestone, full of fQssil 

fragments at base, bryozoa and gastropods above; conglomer¬ 
atic, many quartz grains, base of Lowville 
T 6" Shaly, dove, mud limestone, three beds; very fine, even grained, 
cherty looking 

Leray and Watertown limestones. Emmons had already pointed 
out that the Seven foot tier was closely connected by its lithologic 
character with the underlying formation, and the writer had found, 
while in preceding years collecting the cephalopods of the forma¬ 
tion, that the characteristic cephalopods of the “ Black River ” 
limestone for which the Watertown region is renowned among 
paleontologists, viz, Gonioceras anceps, Hormoceras 
t e n u i f i 1 u m, Lituites undatus and also the “ Black 
River ” coral Columnaria Phalli (— C. alveolata 
auct.) appear already below the Seven foot tier, 1 while at the same 
time the characteristic fossils of the Lowville cited above, especially 
also the omnipresent Tetradium cellulosum, disap¬ 
peared. Since this faunistic extension downward of the “ Black 
River” is coupled with a greater lithologic similarity of the upper¬ 
most 20 feet of the Lowville, as formerly conceived, with the “ Black 
River ” than with the typical Lowville, and this upper portion of 
the Lowville is characterized by seams of chert nodules which 
make good horizon markers, we decided to draw the Lowville-Black 
River line where Tetradium cellulosum abruptly disap¬ 
pears and the chert layers begin. In mapping the “ Black River ” on 
this basis, it was found that, on the whole,.the cherty limestones also 
exhibit the characteristic blocky weathering of the Watertown bed, 

1 While these cephalopods first appear in greater number in the cherty 
beds just below the 7 foot tier, a few stragglers either identical or only 
prenuncial mutations of them, have already been noticed in much earlier 
horizons of the Lowville. Thus Hormoceras tenuifilum 
and a large colony of Columnaria Phalli were noted 11 feet below 
the cherty beds in a Tetradium bed in the section opposite the filter plant at 
Watertown. 



GEOLOGY OF THOUSAND ISLANDS REGION 


85 


and are a unity with them also in that, as a rule, they together form 
a distinct escarpment above the Lowville plateau. In some cases, 
however, the lowest 2 or 3 feet of the chert beds have remained 
clinging in very irregular patches to the underlying Lowville, thus 
forming the serpentine shaped outliers seen in the southern portion 
of the map. 

The authors, under the necessity of drawing a definite boundary 
line between the “ Black River ” and Lowville limestones, which 
would meet the requirements of being lithologically and faunistie- 
ally so well marked that it could be mapped with sufficient ease and 
precision, decided on uniting the cherty beds with the Seven foot 
tier, the two forming a physiographic and economical unit, as demon¬ 
strated by their being quarried together at Chaumont and other 
places. Dr Ulrich’s investigations had shown him a more com¬ 
plete section in Kentucky from which it became apparent that the 
cherty beds are intimately connected there with the rest of the 
Lowville and that the unconformity observed in the Watertown 
region between the cherty beds and the other Lowville represents 
the hiatus which is filled in Kentucky and elsewhere by beds of 
transitional character, while on the other hand the cherty beds 
were found to be also separated by an unconformity from the over- 
lying beds. Since, moreover, the “ Seven foot tier ” or Hall’s 
“ Black River limestone ” is of but local importance, while the Low¬ 
ville, including the cherty beds, is a most persistent unit over a very 
large area, it has been finally deemed preferable by the authors to 
disregard the local conditions of the Watertown region, and to re¬ 
tain the “ cherty beds ” limestone as a subdivision of the Lowville 
limestone, under the term “ Leray 1 limestone,” on account of the 
typical exposures in the town of Leray. 

The following diagram indicates the relations of the beds as now 
understood by us: 


Black River 
group 


r Watertown limestone 




v. 


Lowville formation 


Leray limestone member 
Lowville limestone s. str. 


Since a very irregular surface is observable beween the upper¬ 
most tier of cherty beds, about 6 feet thick, and the underlying beds 
[see section of Klock’s quarry, posted p. 90], and this bed contains 
the cephalopods more frequently than the other cherty beds, Dr 

1 Owing to an error of the printer this word was made to read Leroy 
on page 72 of Museum Bulletin 138. 




86 


NEW YORK STATE MUSEUM 


Ulrich is inclined to unite it with the Seven foot tier or Watertown 
limestone. We adopt here this view, leaving the final decision as to 
the exact boundaries to a future close study of the faunas involved, 
but consider the difficulty of an easy recognition of this boundary 
— located within a lithologic unit — in the field as another practical 
reason for mapping and discussing here the Leray and Watertown 
limestones together. 

Finally, it was found in studying last summer, in company with 
Dr Ami, Professor Cushing and Dr Ulrich, the section at Klock’s 
quarry at Watertown [see below p. 90], that there is properly 
referred to the Watertown also a bed 1^-2 feet thick, of black 
limestone, that still overlies the Seven foot tier. 

With these upward and downward extensions of the formation, 
the limestone will be about 15 feet thick in its type region 
while the Leray limestone is about 13 feet thick, consisting of dark 
gray to black, heavily bedded, dove limestone, with layers of black 
chert nodules. The nodules are more or less scattered through the 
chert beds, forming here and there strings in the section and a dis¬ 
tinct horizon over the whole mapped area near the base of the beds. 
Since large rock exposures of the surface of the Leray limestone are 
frequent in the region, one has often opportunity to observe large 
quantities of these cherts, half weathered out, on the rocks, pre¬ 
senting a flat, cakelike form. Some of the chert beds present, when 
weathered, a peculiarly fucoidal surface through intricate intermix¬ 
ing of the limestone with earthy films, and others are distinctly 
cross-striated. 

The contrast between the massive chert beds and the thinner 
bedded underlying Lowville strata is well shown in plate 20. In 
natural exposures or where the quarry face is weathered, the Water- 
town and Leray formations are readily distinguished from the 
lower Lowville beds by their breaking up into small cubic blocks 
the size of a fist. The beginning of this breaking up, which is ap¬ 
parently due to a reticulate system of mud seams, is seen in plate 
20 and farther progressed in plate 21. Here the rock is so 
weathered that it can be brought down with the pick and is of con¬ 
venient size for road metal. It is also well shown on plate 19, 
where the hat lies just above the boundary line. This picture ex¬ 
hibits especially well the contrast between the evenly and thinner 
bedded typical Lowville limestone and the thick bedded blocky 
weathering Leray and Watertown beds. 

In plate 22 will be found an excellent illustration of the uncon¬ 
formity between the Lowville and Leray limestones. The lower of 



Plate 19 



Leray limestone resting on upper Lowville in quarry at Threemile Bay station, Clayton sheet, look¬ 
ing north. Note the reef layer of Stromatocerium midway in the Lowville. H. L. Fairchild, photo, 1908 

























Plate 20 



<u 


£ o 
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M-i c n 

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^ <D 

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^ aJ C 

O 3 O 

4 —J 

- 

(D O 
Pi C/5 

* £ 
C/D ON 

>» > £ M 
rt £ o ~ 

t-* o PP O 


ro o u 

> rt -d Pd 

> Vh O 

!> rt 

Oji UP 
J O ^ -M 

1 1 <D 


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<U 


£ 

^ 'O c 

<u rt 

M-. C 

O Cj o 

c.y o 3 
o 


Vh O 
<D cn 


. bJD 

S c L 

f> 

a ^ 
^ o ■ 











































GEOLOGY OF THOUSAND ISLANDS REGION 87 

the two massive beds of Leray limestone which appear in the upper 
view is absent in most sections, as in plate 20, where the basal 
Leray bed is the equivalent of the upper bed of plate 22. In addi¬ 
tion most of the Lowville shown in plate 22 is absent in other sec¬ 
tions, the top Lowville bed in plate 20 being the equivalent of the 
basal bed of plate 22. 

1 he Watertown limestone is a solid bank of dark bluish gray to 
black limestone, with rather indistinct bedding planes, very hard 
when fresh, showing numerous small calcite crystals (crinoid 
joints) and a fine reticulation from mud seams and many worm 
tubes. I he mud seams or the earthy intergrowth causes the rock to 
break up most typically in small blocks. 

When fresh the Leray and Watertown limestones, especially the 
Seven foot tier, furnish very large blocks. They are for this rea¬ 
son still extensively quarried at Chaumont where at present the im¬ 
mense blocks required for harbor improvements at Oswego and 
other cities along the Great Lakes are obtained. 

The fact that the 1)4-2 feet of black, knotty, impure limestone 
which overlie the Seven foot tier are separated by a very irregular 
contact from the overlying horizontally bedded Trenton, indicates 
that also this bed. should be properly included in the Watertown 
formation. 

The Seven foot tier and the just mentioned top bed of the Water- 
town formation owe their deep black color to the great amount of 
organic matter in the rock. This saturation with organic matter shows 
itself also in the presence of petroleum in the rock. In the large 
quarries at Chaumont endoceratites and other cephalopods have 
been found whose chambers were partly filled with petroleum and 
the writer was in a cellar in the hotel in Black River village above 
Watertown that is cut in the Watertown limestone and in which 
the petroleum is constantly oozing out of the cellar walls in such 
quantities that the floor is constantly covered with the oil and gal¬ 
lons of it are taken out for cleaning and oiling purposes. The top 
layer of the formation is especially strongly bituminous, and gives 
off a strong odor when struck with the hammer. 

The upper beds of the Black River group of the neighborhood of 
Watertown have become world famous among paleontologists by the 
fine preservation and size of their cephalopods, some of which, notably 
Gonioceras an ceps, have not been found elsewhere. It is 
essentially a cephalopod facies. The straight conchs of Hormo- 
ceras tenuifilum with their large pearly siphuncles, are es¬ 
pecially common on the many ice-polished rock surfaces of the 


88 


NEW YORK STATE MUSEUM 


region and on the rock shelves bordering the river. They are well 
known to the populace as “ fish bones ” which they indeed 
much resemble when broken through the middle. Also two species 
of large Endoceras, distinguished by Hall as Endoceras 
longissimum and E. multitubulatum are frequently 
seen to attain several feet in length and half a foot in diameter. 
Gonioceras anceps, readily recognized by its lyre-shaped 
septa, is rarer and Lituites undatus, another of the char¬ 
acteristic cephalopods of the formation is also less frequently 
observed. There is also a fairly large fauna of brac'hiopods and gas¬ 
tropods present, which, however, has been generally lost sight of 
since the fossils are hard of extraction in the massive rock and 
inconspicuous in comparison with, the large cephalopods. This 
smaller fauna has not yet been described. 

Physiographically the Leray and Watertown limestones form by 
far the most striking feature of the region. Their massiveness and 
hardness as compared with both the underlying typical Lowville 
limestone and the overlying shaly Trenton beds cause them to form 
a distinct plateau or terrace, rising with a frequently vertical escarp¬ 
ment from the Lowville exposure. This escarpment, however, does 
not present the straight face of the Helderberg cuesta but is deeply 
indented or composed of many parallel ridges separated by about 
equally wide valleys, and stretching in fingerlike groups for miles 
upon the Lowville plain. These fingers are especially well seen on 
the map northeast of Limerick, and west of Perch river. They rise 
abruptly from the Lowville plain while the intervales rise more 
gradually to the level of the Watertown limestone plateau. The di¬ 
rection. and form of these fingerlike erosion ridges and their rela¬ 
tion to the prevalent direction of jointing in each special case sug¬ 
gest that they originated from ice plucking between especially deep 
and wide joints. 

The Watertown limestone plateau is in comparison to the small 
thickness of the formation abnormally wide and the Watertown belt 
correspondingly broad on the geological map. This is due to the 
fact that the Trenton rocks are little compact and were easily swept 
off the massive Seven foot tier by the ice. The latter forms thus the 
surface rock over a very large area and is in many places swept clear 
of soil. This fact and the many deep joints make it a very poor 
underground for agricultural purposes, and the plateau is there¬ 
fore frequently wooded, especially so the jagged and deeply jointed 
boundary region along the Lowville belt. Even small brooks have 
frequently formed deep solution and erosion ravines in this forma- 


Plate 21 



Leray limestone overlying Lowville, 2^ miles northwest of Sanford Corners. The view illustrates the 
characteristic weathering of the Leray. Dr Ruedemann is at work on the upper surface of the Lowville. 
H. P. Cushing, photo, 1907 






















































GEOLOGY OF THOUSAND ISLANDS REGION 89 

tion. One of the best examples of such a gorge is that of the 
Perch river at Limerick. Many brooks disappear entirely under 
the W atertown formation, forming long underground courses and 
caves. Several such courses are know in Watertown, where, how¬ 
ever, they have been filled by the damming up of the river. Others 
are known below Watertown and at Black River village. 

Phenomena entirely peculiar to this formation in the region are 
the inkers at the Natural bridge and Limerick. A glance at the 
Watertown-Leray belt on the Clayton sheet north and east of Chau- 
mont bay reveals the fact that in several places the typical Lowville 
beds appear from beneath the Watertown-Leray limestones. These 
inkers consist of elongate strips of Lowville limestone exposed 
along brooks and surrounded on all sides by the Watertown-Leray 
limestones. The conditions which have produced this peculiar and 
rare form of inker are the following: The coincidence of the dip 
of the beds and of the course of the brook and the greater resist¬ 
ance of the underlying Lowville limestone to solution. The brook 
as a rule reaches the inker by a fall, and finally leaves it again by 
very gradually passing again upon the overlying rock. 

A very characteristic example of such an inker is seen along 
Threemile creek and a very large one at the head of Guffin bay. 
The most interesting of all is that below the village of Limerick on 
Perch river. It begins with the fall shown on plate 23 and ends 
above the Natural bridge. At the latter place the river passes under¬ 
ground through a ridge of Watertown-Leray rocks crossing the 
valley. Below the bridge the river reappears for a short distance 
[pi. 38] and disappears again, its course being thence traceable as 
a depression between the cliffs of Watertown-Leray rocks on 
both sides. The depression shows in the different tilting of the 
huge blocks of the Seven foot tier that it is the result of a gradual 
sinking down of the whole mass; and this indicates that the river, 
which has its underground course on the top of the typical Lowville 
beds, is dissolving the Watertown-Leray beds along its course from 
the base upward. There is little doubt that also the inker above the 
Natural bridge, which can not have been produced by normal cor- 
rasion, is the result of solution of the Watertown-Leray beds, and 
that finally also between the Natural bridge and the lake the typical 
Lowville beds will be exposed and the river flow again overground, 
as it already does just below the bridge. 

One of the best exposures of the Watertown-Leray beds is that 
at Klock’s quarry, at the end of Huntington street at Watertown. 
This section which is here inserted, begins close to the base of the 


90 


NEW YORK STATE MUSEUM 


Leray limestone and reaches to the base of the Trenton. The con¬ 
tact with the typical Lowville beds is shown on the opposite side of 
the river and on Diamond island. Plate 24 shows a part of the 
quarry. 

Section at Klock’s quarry, Watertown 

Black, knotty, impure, dark limestone with Strophomena 
filitexta, Leperditia fabulites, Orth is per- 
vetus, Isotelus platycephalus, Orthis tri¬ 
ce n aria, Illaenus a, m e ricanus, etc. 

7 foot tier. Heavy black limestone, with Gonioceras 
anceps, Hormoceras tenui filum 
Dark gray to black, heavily bedded, cross-striated limestone with 
a few cherts, containing also Endoceras, Gonioceras. Resting on 
an irregular surface; base of Watertown limestone 
Irregularly bedded, dark to black, dove colored, fine grained lime¬ 
stone, characterized by weathered, fucoid, earthy markings 
Fine grained dark gray limestone, with cherty layer on top. Cherty 
beds. Bottom not shown 

These chert beds are in this neighborhood underlain by 4-5 feet of 
fine grained dark gray beds with Tetradium cellulosum, 
which also weather blocky like the Watertown limestone. Below 
this are found the dove colored, thinner bedded, typical Tetradium 
beds. 

A series of good sections of the Watertown-Leray limestone are 
exposed in the large quarries about Chaumont. Since, however, the 
Seven foot tier forms here the top of the section and an unknown 
thickness of the same is always eroded, the thicknesses obtained are 
always a minimum. In the large quarries at the head of Chau¬ 
mont' bay the combined beds measure 18 feet; in the big quarries 
along Chaumont river 19 feet of these limestones are found, below 
which 22 feet of typical Lowville beds are exposed to the river edge. 

Trenton limestone. The last of the Lower Siluric stages oc¬ 
curring in the area of the map is the Trenton limestone. It ap¬ 
pears first in outliers near the mouth of Black river, then occupies 
the southern portions of the peninsulas jutting out into Lake On¬ 
tario and finally on the Cape Vincent sheet forms a continuous 
belt. In contrast to the underlying formations and notably its direct 
predecessor, the Watertown limestone, which forms a remarkably 
level plateau with a distinct escarpment at the northern boundary, 
the Trenton appears in well rounded hills, its boundaries approach 
subcircular curves, in contrast to the many fingered and deeply in¬ 
dented Watertown exposures. This is due to the fact that the 
Trenton is a much thicker and at the same time a much less re¬ 
sistant formation, consisting almost entirely of thin bedded lime¬ 
stones with shaly intercalations. It is therefore also much more 
covered by drift and as a rule exposed only along the shore line or 


iy 3 w 

7' 

6 ' 


2.'-2 y 2 " 
5'+ 


Plate 23 



Falls of Perch river at Limerick, Clayton quadrangle; cliffs of Leray limestone overlying Lowville E O Ulrich 
photo, 1908 ‘ ' J 




























Plate 24 



Upper view. Watertown limestone near river at Watertown, showing 
seven foot tier and the upper portion of the cherty bed beneath. 

Lower view. Trenton limestone in creek bank near Threemile Bay, 
Clayton quadrangle. A closer and more detailed view of part of the sec¬ 
tion shown in plate 25. E. O. Ulrich, photo, 1908 

































GEOLOGY OF THOUSAND ISLANDS REGION 91 

on the stoss-seite of the hills. But since the thin limestone slabs 
over the Trenton belt have been incorporated in great quantities 
into the drift, whence they have found their way into the stone 
fences, these stone fences composed of thin Trenton slabs are al¬ 
most the most characteristic feature of the Trenton formation in 
the district and they are remarkably closely bound to the present 
distribution of the Trenton. 

The contact between the Black River and Trenton groups is but 
rarely seen, but where found, it indicates an unconformity, either 
by the irregularity of the contact line, as at the Klock quarry at 
Watertown, or by the presence of a basal conglomerate bed in the 
Trenton as at Threemile Bay. 

The best continuous exposure, or in fact the only good one within 
the boundaries of the mapped area, is that found along a brook at 
the western outskirts of the village of Threemile Bay [pi. 24, 25]. 
This section is given below. Another fairly complete section can 
be obtained from Klock’s quarry to the top of Pinnacle hill at 
Watertown and a third, which however lacks the base, at the west 
end of Carleton island in the St Lawrence river. 

Section of lower Trenton limestone at Threemile Bay 

(generalized) 

i6'-i7' Fine grained thin bedded limestone with shaly intercalations 
3' % Thin bedded limestone layers with shaly intercalations, rich in 

lamellibranchs, gastropods and cephalopods 
10' Fine grained black limestone with shaly partings, in part barren, 

in part full of fossils on shaly partitions, mostly large conical 
or hemispheric bryozoans (Prasopora simulatrix) in 

horizon about 2 feet from base 

3' 6" Black, fine grained limestone full of worm tubes, no other fossils 
5' 6" Gray, crystalline, thin bedded limestone with many crinoid joints 
on top (2 feet) and fine grained dark thin bedded limestone 
below, with shaly intercalations. The limestone beds full of 
brachiopods (Dalmanella, Rafinesquina) and bryozoans 
6' Dark gray to black compact limestone, in strata 1 foot thick with 

thin shaly partings. Very fossiliferous. Dalmanella 

testudinaria, P 1 e c t ambonites sericeus, 

Calymmene, bryozoans (Pachydictya acuta) and 

crinoid joints 

5" Conglomerate bed with crystalline matrix and crinoid joints 
Base of Trenton 
.Black River beds 

It follows from this and the other sections that the Trenton 

begins with a thin conglomeratic bed, on which rest about 6 feet 

of dark gray to black compact limestone, in beds about 1 foot 
thick, with thin shaly partings. The latter are very fossiliferous, 
containing most profusely Dalmanella testudinaria, 
Plectambonites sericeus, Pachydictya acuta 
and crinoid joints. 



92 


NEW YORK STATE MUSEUM 


This black basal limestone of the Trenton contrasts strongly 
with the equally thick underlying Seven foot tier in being a most 
inconspicuous element in the physiography of the region. In fact 
its presence is hardly suspected over the greater part of the area, 
since it is nearly always hidden at the base of the rounded Trenton 
hills. Only where the formations are planed to one level, as about 
Rosiere, is it observed to outcrop as a recognizable belt. 

The remainder of the Trenton, as far as the area of the map is 
concerned, consists then of about 50-60 feet of thin slabby lime¬ 
stones, with shaly intercalations. The limestones are partly gray 
and crystalline with many crinoid joints and partly fine grained, 
dark gray to black. The latter limestone swells sometimes into 
thicker beds (1 foot thick and more) of black limestone which is 
either quite barren of fossils save worm tubes, or as on Carleton 
island, almost entirely composed of» the shells of Plectam bo- 
nit es sericeus. 

Plate 25 shows the general aspect of the thin bedded limestones 
in the creek bed at Threemile Bay and plate 24 which gives a 
closer view of the rocks in the same locality, illustrates the regular 
alternations of limestones and shales in the formation. 

The greater middle and upper part of the Trenton is found in 
the region south of the map, on the other side of Black River bay. 

The fauna of the Trenton has the general aspect of that of the 
formation in other parts of the State. Its details have not yet 
been studied. 

SUMMARY OF PALEOZOIC OSCILLATIONS OF LEVEL 1 

It has been shown that the Potsdam and Theresa formations were 
deposited in the west end of a sagging basin or trough which occu¬ 
pied the general line of the present St Lawrence valley; that the 
deposition began at the east and worked westward, involving our 
region here only in its later stage; and that the depressed trough was 
a westward extension from a similar subsiding trough along the 
Champlain valley line. There the Potsdam is very thick, is followed 
by beds similar to those here called Theresa, and these are overlaid 
by nearly 400 feet of dolomites which have been heretofore classed 
with the Beekmantown formation, as Division A of that formation. 
No such beds as these last appear in our district here, though the 
Potsdam and Theresa may be equivalent to them in time. In the 
Champlain valley also appear four other divisions of the Beekman¬ 
town, with an aggregate thickness in the neighborhood of 1400 feet. 


1 By H. P. Cushing. 



Plate 25 



Thin bedded limestones of lower Trenton age in creek bed at Threemile Bay, Clayton quadrangle, 
looking northwesterly, upstream. H. P. Cushing, photo, 1908 





























GEOLOGY OF THOUSAND ISLANDS REGION 


93 


Ulrich has recently made the important discovery of an uncon¬ 
formity between these beds and Division A, and we coincide in be¬ 
lieving that this division is properly to be classed with the beds below 
rather than with the Beekmantown. The Beekmantown that is 
thinly present in the district here reported upon is not of the Cham¬ 
plain type, but of the Mohawk valley type, lithologically and faunally 
quite like the beds at Little Falls and thence eastward through the 
Mohawk valley, which have heretofore been called the “ fucoidal 
beds,” and which we are proposing to call the Tribes Hill formation. 
This Beekmantown did not come into this northern district from the 
east but from the south, and so far as we know did not extend on 
eastward. * But in passing to the eastward, beyond the limits of the 
region here mapped, Beekmantown beds begin to appear above the 
Theresa, and in our belief are unconformable, though this has not 
yet been demonstrated. Also in our belief this Beekmantown is not 
representative of the lower portion of the formation but of the upper 
portion, and we must go yet farther east to find the lower beds com¬ 
ing in; while the thin edge of Tribes Hill Beekmantown in our dis¬ 
trict here is lowest Beekmantown. Following a condition of uplift 
Beekmantown submergence seems to have commenced fairly simul¬ 
taneously on the east, west and south sides of the Adirondack region. 
Submergence on the west was quickly followed by emergence due to 
a general eastward tilting of the region, so that at Little Falls and 
about Theresa only a slight thickness of the very lowest Beekman¬ 
town was laid down, the Tribes Hill formation. This formation 
steadily thickens to the eastward, along the Mohawk valley, though 
apparently representing nothing but the lowermost Beekmantown. 
The chief area of Beekmantown sedimentation in New York was the 
Champlain valley trough and its prolongation southward. Along 
with the steady subsidence in that trough seems to have gone a sub¬ 
sidence of the St Lawrence trough which, like the previous Potsdam 
subsidence, seems to have commenced at the east and worked west¬ 
ward ; so that, in that trough, the lowest Beekmantown is absent, and 
steadily higher beds are at the base going west. The extreme west¬ 
ward reach of this Beekmantown depression of the St Lawrence 
trough seems never to have reached the Theresa district, where the 
only Beekmantown represented is the thin base of the Tribes Hill 
formation of the Mohawk Beekmantown type. L T ntil the Beekman¬ 
town on the north side of the Adirondacks has received more 
thorough study, this view of Beekmantown conditions in the St Law* 
rence trough can not be regarded as based on sufficient evidence, 
though evidence on the other three sides of the Adirondack region 


94 


NEW YORK STATE MUSEUM 


in respect to these conditions seems now quite well substantiated. 
Our immediate district in late Cambric (Ozarkic) time sloped to the 
east and received the thin deposit of Potsdam and Theresa beds laid 
down in the western end of the St Lawrence trough. Uplift fol¬ 
lowed throughout New York, producmg unconformity between these 
beds and those of the Beekmantown which follow. Beekmantown 
subsidence seems to have commenced simultaneously on the east, 
west and south sides of the Adirondacks, with a tilting of the 
surface in our district here, so that its slope was to the south¬ 
west, instead of to the east. This was quickly followed by tilt¬ 
ing of the whole region to the east, stopping Beekmantown de¬ 
posit on the west and south sides of the Adirondacks and confining 
it to the eastern trough. From this trough a bay seems to have de¬ 
veloped westward up the St Lawrence trough, during Beekmantown 
time. The Beekmantown was brought to a close by another uplift 
of the entire northern New York region. In the Theresa district 
this time gap was a long one during which 1000 feet or more of 
Beekmantown rocks were deposited in the Champlain trough, and a 
much greater thickness in other regions. 

Through these early times then our district had a general slope of 
its surface toward the east, though with an intervening time of short 
duration during which the slope was to the southwest. There were 
three depressions, alternating with three elevations of the surface, 
though apparently the deposits of the third depression just failed to 
reach the district. 

In the Champlain valley the Beekmantown is succeeded by the 
Chazy limestone formation, the two being separated by a slight un¬ 
conformity, indicating that the Beekmantown was followed, as it had 
been preceded, by general uplift of the whole area. Depression was 
then renewed in that trough for the third time, and for the third 
time a bay was developed westward from it. This Chazy bay, how¬ 
ever, seems not to have reached as far westward as the preceding 
Beekmantown bay, and certainly fell many miles short of reaching 
our district here. 

The Champlain Chazy is divided into lower, middle and upper sub¬ 
divisions. The typical Chazy rocks are limited to the Champlain 
trough and its prolongation north and south. This trough was 
separated from a much larger depressed area to the westward, by a 
land barrier, which prevented the passage of organisms from the one 
basin to the other. At the same time therefore in which the Chazy 
rocks were being deposited in the Champlain trough, other deposits, 
characterized by a different fauna, were forming to the west of them, 


GEOLOGY OF THOUSAND ISLANDS REGION 


95 


and the rocks of this group are known as the Stones River forma¬ 
tion. During Chazy time the depression in which Stones River rocks 
were forming was encroaching upon northern New York from the 
south and west, and by the close of the middle Chazy this depression 
had become sufficiently extensive to involve our district here, and the 
deposition of the Pamelia formation commenced, the Pamelia being 
the local New York facies of the Stones River formation, and repre¬ 
senting only a portion of its upper division. The tilting of our dis¬ 
trict necessary to permit of this invasion from the southwest, 
changed its former easterly inclination to a southwesterly one, over 
most of the district; but apparently this change of slope died out on 
the eastern edge of the Alexandria sheet, east of which lay the land 
area which separated the Pamelia basin from the Chazy basin; and 
this received no westerly tilt, but chiefly retained its old slope to the 
east. This in our view is the origin of the Frontenac axis, as the 
narrow isthmus of Precambric-rocks which connects the main Adi¬ 
rondack Precambric mass with the great Canadian area of these 
rocks, and which passes through our district here, is called. It 
simply represents an axis of the old Precambric floor which became 
less depressed than the portions of the floor east and west from it. 
The Potsdam-Beekmantown-Chazy depressions sagged the district to 
the east, covering it with steadily increasing thickness of their de¬ 
posits in that direction; the Pamelia depression sagged the district 
to the west, and in that direction the overlying deposits steadily in¬ 
crease in thickness. The Frontenac axis is the pivotal district be¬ 
tween the two, where sagging was least and deposit thinnest. Sub¬ 
sequent erosion could thus wear away this thin cover and bring the 
Precambric back to daylight, along this line, as it has done, while yet 
the thicker cover, east and west, in part remains. 

According to Ulrich the Pamelia formation is of age intermediate 
between the middle and upper Chazy of the Champlain valley, but 
little sedimentation having taken place there in Pamelia time; in 
other words while this region was subsiding and accumulating de¬ 
posit, that ceased to subside. With the cessation of Pamelia deposi¬ 
tion on the west, resulting in the unconformity between the Pamelia 
and Lowville, deposition was renewed on the east and the upper 
Chazy was laid down. In like manner the Lowville formation is 
but slightly represented in the Champlain valley, though well de¬ 
veloped here, as if, with renewed subsidence here it again ceased 
there. Toward the close of the Lowville, uplift occurred on the 
northwest giving rise to the unconformity between the main mass of 
the Lowville and the Leray limestone. At the same time depression 


96 


NEW YORK STATE MUSEUM 


began in the Champlain region, and what has there been called 
Black River limestone commenced its accumulation. This deposit 
consists of a small thickness of typical Lowville at the base, the 
equivalent of the Leray limestone at the summit, and interme¬ 
diate beds which represent the Lowville-Leray hiatus of the north¬ 
west ; while the Watertown limestone is lacking. With our sug¬ 
gested nomenclature this may still be properly called Black River, 
while on any other arrangement it could not be so called. The 
Mohawk region was close to the shore line throughout Black River 
time and received only the very thin, near-shore edge of the deposits 
of the group, never more than a few feet thick, often practically 
absent and varying much in horizon from place to place. 

At the close of the Leray, uplift was widespread and the Water- 
town limestone is practically absent except in that locality, in strong 
contrast with the widespread occurrence of the preceding Leray. 
Then followed subsidence on the east with accumulation of the 
Amsterdam limestone, which is wholly absent on the west. Then 
ensued on all sides of the region the Trenton submergence; lime¬ 
stone quickly followed by black shale on the east so that the bulk 
of the eastern Trenton is of shale; the shale gradually encroaching 
westward, but the western Trenton, of the type locality and north¬ 
ward, remaining of limestone throughout. The black shale of the 
Utica followed, with northern New York more largely submerged 
than at any other period in its geologic history, the Grenville pos¬ 
sibly excepted. Possibly the Adirondack island was entirely sub¬ 
merged. With the close of the Utica local elevations began to ap¬ 
pear, and by the close of the Ordovicic much of the State was again 
unsubmerged. Since then most of northern New York has re¬ 
mained a land area. The appended chart will, it is hoped, aid in 
the understanding of these views. 


GEOLOGY OF THOUSAND ISLANDS REGION 


97 


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9 8 


NEW YORK STATE MUSEUM 


Dip of the Paleozoic rocks 

It has just been stated that the Paleozoic rocks dip away from the 
Frontenac axis in both directions, and it is desirable to scrutinize the 
matter somewhat more closely. 

In the southeastern corner of the Theresa quadrangle the base of 
the Leray limestone is at 600 feet altitude. The general line 
of outcrop of the formation runs across the mapped area in a west- 
northwest direction, and on the Cape Vincent sheet passes beneath 
the river level 247 feet. This is a drop in altitude of 353 feet in 27 
miles, about 13 feet to the mile, in this west-northwest direction. In 
the direction of due west it is about 16 feet per mile, as nearly as can 
be calculated. Neither one of these, however, gives the direction of 
true dip, which lies somewhere between s. 30° w. and s. 45 0 w. At 
Adams, which lies some 30 miles somewhat west of south of the vil¬ 
lage of Theresa, three deep wells were drilled for gas some years 
ago, and the records of these wells are given by Orton. 1 Fairchild, 
who is familiar with the region, has also supplied me with data. 
Starting on ground whose altitude is approximately 600 feet above 
sea level, these wells reached the Precambric at depths of 915, 950 
and 960 feet respectively. The Precambric surface is here approxi¬ 
mately 315 feet below sea level, while at Theresa it averages about 
400 feet above the sea. In the 30 miles then, this surface drops 715 
feet, or nearly 24 feet to the mile. This however is the slope of the 
Precambric surface, which may or may not coincide with the dip, 
and in all probability does not. If the different limestones could be 
distinguished in the well records the data would be at hand for deter¬ 
mining the dip, but this is unfortunately not the case. If the Paleozoic 
rocks thicken in that direction, the dip is somewhat less than the 
above figure ; if they thin it is somewhat greater. At Adams the 
Potsdam and Theresa formations, 150 feet in thickness about 
Theresa, have disappeared. The other formations are present how¬ 
ever and are unquestionably thicker than at Theresa. Beginning 
near the summit of the Trenton, the drill at Adams penetrated 
through 900 feet of limestone before reaching the Precambric. If 
we knew the thickness of the Trenton in our district here we should 
again have the necessary data, but all the upper Trenton lies to the 
south of the map limits, and the thickness of the formation has never 
been accurately measured so far as we know. It is certainly as much 
as 500 feet and may be a hundred feet more than that. We have 
then at least 800 feet of Paleozoic rocks here below the Utica, and 
perhaps 900. It seems therefore that the thickening of the upper 


1 N. Y. State Mus. Bui. 30, p. 457-58. 



GEOLOGY OF THOUSAND ISLANDS REGION 


99 


limestones at Adams just about compensates for the disappearance 
of the Potsdam and Theresa formations there, and that the dip is 
substantially the same as the fall of the rock floor, or 24 feet per 
mile. At most there is a deduction of but 100 feet to be made, 
amounting to 3 feet a mile in 30 miles, and reducing the total to 21 
feet per mile. If, as is likely, this is still not the direction of true 
dip, being too nearly due south,' the figure must be somewhat en¬ 
larged, and in all likelihood it amounts to from 25 to 30 feet per 
mile, certainly not exceeding 35 feet. 

It is of interest to note that this dip, and this slope of the 
Precambric floor, are much less than those worked out in the 
upper Mohawk valley by Miller and myself (Remsen and Little 
Falls quadrangles) where the dips approach 100 feet per mile to 
the southwest, and the Precambric floor underneath has a slope 
exceeding that of the dip by some 30 feet. The matter of the 
present dips is simply the sum total of tipping given to the rocks 
since they were deposited, by the various oscillatory movements 
to which each region has been subjected since; showing that the 
Mohawk rocks have been somewhat more tipped than those 
here. The matter of floor slope however shows clearly that the 
shore line in the Mohawk region had a somewhat greater cant 
than was the case here ? producing more rapid overlap of the 
rocks there. 

In the northeast portion of the Alexandria sheet the dip has 
flattened out to practical horizontally, Potsdam with overly¬ 
ing Theresa forming the river bluffs. Going east, down the 
river, the dip soon changes to the northeast, carrying these 
formations beneath the water and the westerly edge of the Beek- 
mantown becomes the surface rock, beyond which, for many 
miles, the river flows through Beekmantown rocks, all with 
slight northerly dip. These are the deposits of the eastern basin, 
and received no tilt to the west. 

ROCK STRUCTURES 1 
Foliation 

Foliation is the name applied to the species of cleavage de¬ 
veloped in rocks which, under compression, have wholly or 
largely- recrystallized. The cleavage is chiefly due to the ar¬ 
rangement which the compression enforces on many of the re¬ 
crystallizing minerals, which tend to develop in the shape of 


1 By H. P. Cushing. 

4 




IOO 


NEW YORK STATE MUSEUM 


leaves or needles; so that, in so far as the mineral particles have 
longer diameters, or scalelike shapes, these develop in the planes 
at right angles to the direction of compression and give the rock 
a tendency to split along them. Obviously a better cleavage 
will usually develop in rocks which consist of more than one 
mineral than in those composed chiefly of a single one, and in 
the former case a better cleavage will appear where there is 
large difference in the characters of the different mineral species 
than where this difference is small. Thus a quartz-mica rock, or 
a feldspar-hornblende rock, will be apt to have a much better 
foliation than a quartz-feldspar rock. 

A rock in which a good foliation cleavage is developed, so that 
it tends to split rather evenly and readily is said to be schistose, 
or called a schist. When the foliation is less even, and less 
ready, gneissoid is the adjective, and gneiss the substantive em¬ 
ployed. As a general rule certain sediments, such as shales and 
impure (or shaly) limestones and sandstones, recrystallize into 
schists, while pure sandstones and limestones, which recrystallize 
into pure quartz or pure calcite rocks, and consist chiefly of the 
one mineral, show little or no foliation. Igneous rocks are 
usually already crystalline, and in general do not recrystallize 
with as prominent a foliation as do many of the sediments, hence 
are more prone to form gneisses than schists. 

Foliation in the Grenville rocks. The pure Grenville quartzites 
and limestones are now quite massive crystalline rocks with 
little or no foliation, though there is some development of frac¬ 
ture cleavage in the resistant quartzites, which is lacking in the 
more plastic limestones. Even the quite impure limestones show 
usually but little foliation. The impure quartzites have de¬ 
veloped either pyroxene or mica on recrystallizing, usually the 
former, and this rock has poor cleavage while the latter become 
quartz schists. In the mass of Grenville rocks of varying com¬ 
position to which the general name of the “ schist series ” has 
been applied, foliation cleavage is in general prominent. But 
even here rocks with considerable development of minerals of 
the mica type are relatively rare, and since such constitute the 
most prominently foliated rocks, their rarity militates against the 
prominence of foliation in the series, the bulk of which would be 
better classed as gneissoid, rather than as schistose. Some varie¬ 
ties of the amphibolites are quite micaceous and hence possess 
good foliation cleavage. The green schists and ordinary amphi¬ 
bolites usually show fair foliation only, and a general assemblage 


GEOLOGY OF THOUSAND ISLANDS REGION 


IOI 


of all the types of Grenville rocks of the district does not give 
the impression of a group of extra well foliated rocks. This is 
largely due to the comparative scarcity of micas, and of amphi- 
boles of slender habit, in the series and the abundance of 
pyroxenes and of stout amphiboles. This again is a result of 
the prominently anamorphic character of the metamorphism. 

The foliation of the Grenville rocks is parallel to the bedding. 
In the schist series rapid alternations of materials of somewhat 
varying composition is a feature, producing a very well banded 
structure, sometimes so fine as to somewhat mimic a coarse 
foliation. 

Foliation of the granite gneiss. It has been shown that the 
Laurentian granite is characterized by frequent inclusions of 
older rocks, chiefly of amphibolitic types, and that there is also 
present much intermediate material, resulting from the soaking 
of the amphibolite with granitic substance, or from its actual 
digestion by the granite. The rock itself contains normally 
some mica or hornblende, and hence, through the greater por¬ 
tion of the mass these minerals are present in varying quantity, 
and the rock is susceptible of foliation development under the 
proper conditions. That such conditions have obtained is clearly 
shown, a foliation cleavage of varying prominence appearing 
nearly everywhere, though it becomes very obscure in those 
relatively small portions of the mass which consist solely of 
quartz and feldspar. The general rock is thus foliated but with 
foliation of the crude type which proclaims the rock a gneiss, 
rather than a schist. 

The foliation structure of the granite gneiss conforms everywhere 
in dip and strike to that of the adjacent Grenville rocks. While 
this by no means excludes the possibility that the Grenville rocks 
may have been compressed and foliated prior to the intrusion of 
the granite, it does demonstrate that both sets of rocks have 
undergone compression in common, subsequent to this intrusion. 
It is quite possible that much of this compression was a result 
of the actual intrusion, and that the granite gneiss actually 
solidified with a foliated structure. This is not at all uncommon 
in great bathylithic intrusions, which, in order to make a place 
for themselves, must endeavor to shoulder aside the rocks previ¬ 
ously occupying the space. This shouldering pressure exerted 
on the adjacent rocks under bathylithic, or deep seated, condi¬ 
tions, that is with a thick cover of overlying rocks, tends to 
give the rocks thus compressed a foliation which parallels the 


102 


NEW YORK STATE MUSEUM 


margins of the bathylith, and hence boxes the compass in direc¬ 
tion. At the same time the rock of the bathylith, while solidify¬ 
ing, may develop a similar and parallel foliation. 

While it can not be affirmed that such results were not brought 
about in the region, it can be positively stated that, if so, they 
have been so disguised by subsequent compressive stresses that 
the effects of the two can not now be successfully disentangled. 
This is shown in several ways: (a) the microscopic study of the 
granite gneiss indicates that, to a considerable extent at least, 
its foliation is due to recrystallization rather than to original 
crystallization, in other words the rock has been much crushed 
and somewhat recrystallized under compressive stress, since it 
originally congealed; (b) these later stresses seem to have been 
severe enough to materially change the shape of. the bathylithic 
masses, elongating them greatly in the northeast-southwest direction 
and correspondingly pinching them together in the direction at right 
angles to this; (c) instead of the foliation running around the 
bathyliths, with parallelism to the margin, it retains its general 
northeast-southwest strike throughout the region, independendently 
of these margins, so that either no such marginal foliation was 
ever developed, or else it has been practically eliminated by the 
subsequent compression; ( d ) later igneous rocks than the granite 
gneiss have also had a foliation developed as a result of com¬ 
pression, most prominently in the earlier ones, and with steady 
decrease in prominence in the later. 

It thus appears most probable that the general parallelism of 
the foliation of all the Precambric rocks, and its substantial uni¬ 
formity in direction throughout the region, is chiefly owing to 
compression of later date than that of the Laurentian granite in¬ 
trusion. This appears increasingly true in going eastward into, 
and across, the Adirondack region. The rocks show steady in¬ 
crease in amount of metamorphism, in degree of mashing and re¬ 
crystallization, in uniformity of foliation, and in obliteration of 
such possible structures as primary foliation. Some of this in¬ 
crease may be ascribable to greater thickness of cover, but the 
evidence of thoroughgoing compression of much later date than 
the Laurentian, is very clear. 

Foliation of the later igneous rocks. The Alexandria and 
Theresa syenites seem closest to the Laurentian in age, among 
the conspicuous igneous rocks of the district. The Alexandria 
syenite shows cores of fairly massive rock, not foliated though 
with a considerable amount of crushing. But the porphyritic 


GEOLOGY OF THOUSAND ISLANDS REGION ’ 


103 


border phase is considerably metamorphosed and converted into 
a thorough gneiss, with the augen (the uncrushed remnants of 
original large feldspar crystals) alined in the direction of the 
foliation. This also is coincident with the direction of foliation 
in the Grenville and Laurentian rocks. While it is true that the 
metamorphism exhibited by the syenite is not as severe in degree 
as that shown by the other two groups, it is clear that there was 
severe compression of the region at, or after, the time of syenite 
intrusion, and compression under quite similar conditions as 
regards overlying load. 

The Theresa syenite does not appear so foliated as does the 
Alexandria, chiefly because of difference in composition, which 
shows itself mineralogically in the much slighter development of 
hornblende and mica, the rock consisting largely of feldspar. It 
also lacks the coarsely porphyritic phase. Foliation is therefore 
much less prominent, though the rock shows crushing and recrys¬ 
tallization in degree quite comparable with the other. It has 
therefore likely experienced compression of substantially equiva¬ 
lent amount and duration, but its composition prohibits good 
foliation development. 

Pic ton granite. This, the latest of the early intrusives of 
the district, shows little or no foliation, and to the eye gives 
little evidence of crushing, as if the intrusion was wholly sub¬ 
sequent to the great squeezing of the region. The thin sections 
bear out this impression. 

This evidence would seem to indicate compressive stresses ap¬ 
plied at intervals through a considerable length of time during 
the region’s very early history, with gradual cessation, and that 
the foliation structure in the Grenville and Laurentian rocks 
must be due to something more than the pressure and heat fur¬ 
nished by the intrusion of the Laurentian granites. 

Joints 

The clean-cut divisional planes, usually highly inclined, which 
occur in most rocks, are termed joints. While generally vertical, 
or nearly so, they may have any inclination. In a “ joint set ” 
the divisional planes show a close approach to parallelism, both 
in trend and in inclination. In most regions more than one set 
is present. When there are two, the usual condition is that they 
are approximately at right angles to one another. Often there 
are more than two sets as is the case in our region here. When 
four sets are present it is usually found that they are separable 


104 


NEW YORK STATE MUSEUM 


into two pairs, each pair consisting of two joint sets at right 
angles to one another, and the joints of one pair bisecting the 
angles between the joints of the other pair. In such districts it 
is seldom the case that all four joint sets are exhibited in a 
single rock exposure, two or perhaps three of the four showing, 
rather than the whole number. In many, if not in most, regions 
where four or more joint sets occur, it is found that one pair 
tends to north-south and east-west directions, with another pair 
showing northeast and northwest trends. The joint planes often 
curve somewhat, so that the compass direction of a given set may 
vary through a considerable number of degrees. This tendency 
much increases the difficulty of discrimination between the dif¬ 
ferent sets in districts where more than four are present, as is 
quite frequently the case. 

In folded rocks the character of the jointing differs considerably 
from that found in rocks not folded. Since in our region here we 
have rock masses of each sort, Precambric rocks which have been 
greatly compressed and folded, and overlying Paleozoic rocks which 
are comparatively undisturbed, it will be convenient to consider 
them separately. 

In the Precambric rocks. The diagram [fig. 5] presents a 
summation of the readings taken on the joints of the Precambric 
rocks of the district included in the maps. They are comparatively 
few in number, partly because of the comparatively small area 
which presents these rocks at the surface, and partly because the" 
joints were found to be so irregular that no satisfactory readings 
could be obtained in many exposures. The rocks are not as abun¬ 
dantly jointed, nor are the joints as clear-cut as usual in the Adiron¬ 
dack region. 

In closely folded sediments, such as the Grenville, joints are apt 
to be present as a result of compression, and to have their direc¬ 
tions controlled to a considerable extent by the folds, or in other 
words by the strike and dip of the folded sediments. These have 
been shown to have a general northeast strike throughout the dis¬ 
trict, though locally varying in direction through more than 90°. 
The more usual direction however is n. 40° e.-n. 6o° e. Two sets of 
, joints are present which have the same surface trend, that of the 
rock strike, the one set controlled by the dip and having approxi¬ 
mately the same inclination, the other inclined in the opposite direc¬ 
tion, or to the southwest, and closely at right angles to the first 


GEOLOGY OF THOUSAND ISLANDS REGION 


105 


set. Figure 4 is an attempt to illustrate these relations. These two 
joint sets, both having the same strike as the Grenville rocks, are 
much the most prominent of the joints which these rocks show, and 



Fig. 4 Sketch and section of alternating quartzite and amphibolite bands of Gren¬ 
ville series, the quartzites forming low ridges on the surface. The line A represents the 
direction of the joints which follow the dip, the line B that of those at right angles to the 
first set, and C represents the direction in which both sets cut the surface 

conspicuous at every good exposure of the Grenville schists or 
quartzites, though much less conspicuous in the limestones. The 
quarry face in plate 2 is on the dip joints, here steep, and the other 
set are quite flat and show well in the view, as does also a vertical 
set of northwest joints. So common are they that they soon came to 
be recognized as a matter of course, which it was superfluous 
to chronicle in the notebook. Hence the number of observations 
on joints striking n. 40° e.-n. 6o° e. shown on the diagram [fig. 
5] is misleading as to their abundance and importance. The com- 



Fig. s Diagram to indicate the number of readings on joint directions in the Pre¬ 
cambric rocks of the district for each s° point of the compass, the outer row of figures 
giving this number, and the inner row the compass degrees, corrected for variation 

paratively slight variation in the number of readings for all points 
between n. 30° e. and east is however a result of, and indication of, 
the swerving of these joints with swerve in the rock strike. 








IO6 NEW YORK STATE MUSEUM 

The foliation of the Laurentian granite gneiss, and of the gneis- 
soid portion of the Alexandria syenite is concordant with that of 
the Grenville rocks, and in them these same joint sets are developed, 
though in a much less prominent way. In the more massive igne¬ 
ous rocks they are replaced by a set of vertical, northeast joints. 

At right angles to the set, or sets, of northeast joints is a set 
with northwest trend, with planes nearly or quite vertical, and rang¬ 
ing from n. 40° w. to n. 55 0 w. in direction, 27 of the readings 
falling within those limits. A less conspicuous east-west set is also 
indicated by the 12 readings between n. 70° w. and n. 8o° w., to¬ 
gether with the 14 between n. 8o° e. and e. As seen in the field 
also this set is more variable and less prominent than the north¬ 
west set. The number of northerly readings is not great, and is 
spread rather uniformly over 50° of compass range, coinciding with 
the impression given in the field as to the comparative scarcity and 
great irregularity of that joint set. 

Notwithstanding the rather small number of total readings the 
diagram shows that 30 out of the possible number of 36 different 
5 0 directions are represented. Nowhere in the field were more than 
four sets of joints noted in a given rock exposure, and all the 
joints showed considerable tendency to curve and vary in direction, 
leading to the belief that this spreading of the readings is owing 
to this variability and in no wise indicative of a great number of 
joint sets. 

Locally the more rigid of the Precambric rocks, the quartzites 
and granites, are excessively jointed, the joints being very close 
spaced, chopping up the rock into small, angular blocks [see pi. 
3]. In such places signs of slipping are usually to be made out. 
These so called “ shear zones ” result from readjustment under com¬ 
pression under conditions such that these rigid rocks fractured and 
slipped along the fractures, while those less rigid, the limestones for 
example, effected readjustment in other manner. 

That the Precambric rocks were jointed prior to the deposition of 
the Potsdam sandstone is conclusively shown, firstly by the absence 
in the Paleozoic rocks of compression joints and shear zones, and 
secondly by the occurrence of joint cracks in the Grenville lime¬ 
stones which became widened by solution and in that condition were 
filled with sand as the Potsdam sands commenced to be deposited. 
In the few cases in the district where contacts between Potsdam 
and Grenville limestone are exposed these features appear [see 
fig- L P- 58] and are apparently widespread. 


GEOLOGY OF THOUSAND ISLANDS REGION 107 

In the Paleozoic rocks. In the Paleozoic Rocks of the district, 
Potsdam to irenton, the joints are vertical, or nearly so, and show 
also considerable variability in direction, though this seems not quite 
so pronounced as is the case in the Precambric. Figure 6 gives 
a diagrammatic summary of 280 readings on these joints, and shows 
again a spreading to all points of the compass, 34 of the 36 possible 



Fig. 6 Diagram, similar to that of the preceding figure, of the joints of the Paleozoic 
rocks 

directions being represented. The great number of readings in the 
direction n. 70° e.-n. 80 0 e. constitutes the most prominent feature. 
The next point at which readings are concentrated is the n. 50° w. 
direction, but readings with this general trend are spread from 
n. 40° w. to n. 65° w., in other words these joints are somewhat 
less true in direction than those of the preceding set, which may 
however be regarded as extending from n. 60 0 e. to n. 8o° e. A 
third direction of more abundant readings, from n. 20° e. to n. 40° e. 
is also shown, while the fourth direction, n. io° w.-n: 30° w. is the 
least prominent of all. This last, however, is the one at right angles 
to the first, and most prominent, set. As thus outlined there are 
99 readings for the first set, 81 for the second,-45 for the third and 
but 25 for the fourth. There remain 40 readings which lie wholly 
without these groups. It is to be noted that the mean directions of 
the four groups do not correspond with the cardinal points of the 
compass, but show a general deviation of 20° from them. 

In the field the majority of the exposures exhibit but two good 
joint sets, though usually a third quite irregular set is present. With 
two good sets shown it is the exception that they are at right angles, 
and it is the east-west set and either the northeast or the northwest 
set with it, that usually appear. Often all three of these sets appear 
with lack of only the north-south set, and with the east-west set 
customarily the most prominent and regular. On bared rock sur- 





io8 


NEW YORK STATE MUSEUM 


faces therefore the joints ordinarily divide the exposure into rhom- 
boidal, rather than rectangular blocks. In plates 15, 20 and 23 
joints are well shown. 

The limestones of the district exhibit, in general, more abundant, 
more regular, and more clean cut joints than does the Potsdam sand¬ 
stone. The limestones moreover are all somewhat soluble in rain 
water and underground water, the Black River and some of the 
Lowville beds being preeminent in this respect. The glacial depos¬ 
its over the district are in rather scant amount, there being much 
bare rock exposed, and much more only thinly coated with soil. 
On the bared limestone surfaces the widening of the joint cracks 
produced by slow solvent action of rain water which passes under¬ 
ground along them, is magnificently shown [pi. 26, 27], most 
impressively perhaps in the Black River beds but almost equally 
well in the upper Lowville. In many fields which might other¬ 
wise be available for pasturage, the cattle must be carefully ex¬ 
cluded, otherwise they fall into, and become tightly wedged in these 
gaping fissures. During our field work we came by chance upon 
a poor, stray cow in such plight in the vicinity of Limerick, tightly 
wedged in a fissure of sufficient size so that the animal’s back was 
well below the ground surface. 

Down these widened joint cracks also the streams go underground, 
so that surface streams are infrequent in the Black River and upper 
Lowville districts. Beneath, this downward tendency is checked by 
the less soluble character of the remainder of the Lowville, on the 
upper surface of which these waters run along, eating away under¬ 
ground channels of considerable size in the soluble layers just above. 
In their early stages these channels are thoroughly roofed over, but 
as time goes on the roof tends to disappear, either by caving in be¬ 
cause of lack of support by the widened channel underneath, or by 
slow dissolving away of the rocks above, thus bringing daylight 
down to the upper part of the tunnel. The matter will receive 
more detailed discussion when treating of the general drainage, but 
the details of the process and its varying stages are most excel¬ 
lently illustrated in the region [pi. 35-38]. While it is in many 
cases impossible to distinguish between preglacial and postglacial 
solution, it is nevertheless clear that much of this limestone removal 
is postglacial. 

Folds 

The rocks of the district exhibit various degrees of folding. The 
Grenville sediments are closely and intricately folded; the Paleozoic 
rocks show slight folding of Paleozoic date; and the same rocks 


Plate 26 









Bared surface of Leray limestone in field iy 2 miles west of Sanford Corners, Theresa quadrangle, show- 
g solution along joints. H. P. Cushing, photo, 1907 



















Plate 27 



turf-filled joints. H. P. Cushing, photo, 1907 
























■ 
























GEOLOGY OF THOUSAND ISLANDS REGION 


109 


show occasional small surface folds, or buckles, produced since the 
ice sheet vanished from the region. 

Precambric folding. It has been shown that the Grenville beds 
are now found for the most part in highly inclined condition, 
dips of less than 45 0 being relatively rare, while those approach¬ 
ing verticality are common. Averaging the dips of the entire 
formation would give a result of at least a 55 0 to 60 0 dip. It has 
also been shown that the dip is not everywhere in the same direc¬ 
tion but that, with the general direction of strike to the northeast- 
southwest, the dip, while prevalently to the northwest, becomes at 
times southeast. The southeast dips prevail over a belt of country 
some 4 miles in breadth in the Butterfield lake district of the 

Alexandria sheet. In the country lying south of this belt the dips 

are all to the northwest. In the other direction the Grenville is 

badly cut out by the syenite and granite of the Alexandria and 

Picton bathyliths, but such as remains shows very steep to verti¬ 
cal dips, chiefly to the northwest. The highly tilted condition of 
the rock series, and these changing dips seem certainly indicative 
of folding. Moreover many exposures exhibit small folds of ex¬ 
ceedingly compressed type, often accompanied by extreme plica¬ 
tion. It is reasonable to suppose that these are merely secondary, 
or minor, folds superimposed upon folds of much larger scale. 

In order to demonstrate the presence of these larger folds it 
is necessary that the order of superposition of the various Gren¬ 
ville beds should be worked out, and in the early stages of the 
field work it was hoped that this might be done. It is possible 
that it might have been successfully accomplished had large scale 
maps, say 4 inches to the mile, been available. But the structure is 
so complicated, the dips so steep, the folds so compressed, the 
series so greatly cut out by the igneous rocks, or so modified in 
character by them, and so much of the territory is yet covered by 
the Paleozoic rocks, that no certainty as to the Grenville succession 
could be arrived at with the maps in hand. Certain suggestions 
may however be made. 

Inspection of the maps will show that the Indian river, from 
Theresa northward to the point where it passes ofif the Alexandria 
sheet, follows a broad belt of Grenville limestone, averaging some¬ 
what more than a mile in breadth. Except for being much cut up 
by granite dikes and stocks, it is quite pure limestone. The dips 
are steadily to the northwest, and flatter than the usual Grenville 
dips, averaging about 45 °, and hence indicating a thickness of 
about 4000 feet for the limestone. A few miles to the northward, 


no 


NEW YORK STATE MUSEUM 


on the Alexandria sheet, what appears to be a quite similar broad 
belt of limestone borders the west side of Butterfield lake. It is 
however so much concealed by overlying Potsdam sandstone that 
some uncertainty attaches to its extent and purity. But it has a 
breadth of outcrop quite comparable to that of the Indian river 
belt, and seems to consist chiefly of pure limestone. Its dips are 
prevalently to the southeast, and somewhat steeper than in the 
previous case, averaging 6o°. This means a thickness substantially 
the same as in the other case, and strongly suggests that the two are 
parallel outcrops of the same great limestone belt, and that, since 
they dip toward one another, the structure is synclinal. If this 
be the true interpretation then the schists, amphibolites and quart¬ 
zites which lie between the two limestone belts, rest on the limestone 
and hence are younger, with the rather massive quartzites about 
Sixberry and Millsite lakes as the youngest of all; while the schists 
to the northwest on the Alexandria quadrangle, and to the south¬ 
east on the Theresa quadrangle, underlie the limestone and are 
older. Figure 7 will illustrate the suggested structure. 


/ 





Fig. 7 Section to illustrate the structure suggested by the Grenville rocks, on a scale of 
4 miles to the inch; s=schists, c=crystalline limestone, q=quartzite 


There are, however, two alternative views in regard to this struc¬ 
ture which may be held. It is possible that these two thick lime¬ 
stone masses may be separate beds, the one overlying the other and 
separated from it by the thickness of schist and quartzite which 
lies between. This involves the assumption that the series, though 
greatly tipped, is not folded and hence that no bed is cut by the 
present surface along more than one line. Since, however, small 
folds are certainly present in considerable number, the changing dips 
indicate the presence of greater ones, and as we have here two 
great lines of limestone outcrop, the rock showing much the same 







GEOLOGY OF THOUSAND ISLANDS REGION 


III 


thickness in each, and the two dipping toward one another, this sup¬ 
position seems improbable in high degree. There seems no direct 
evidence for it and much against it. 

The other alternative is that the structure here is anticlinal in¬ 
stead of synclinal. This is a possible interpretation of it in spite 
of the fact that the two limestones dip toward one another. Long 
continued and severe compression may so closely compress rock 
folds as to cause them to pass into the fan fold type as illustrated 
in figure 8. Such folds are so pinched that vertical dips prevail 
centrally, along the axes, and the dips farther away converge 

toward the axis in the anticlines, ^-. 

instead O'f in the synclines as in the /" 

previous case. In that also the dips / '' \ 

flatten in the vicinity of the axis of ' / .... 

the fold, and pass from one direc¬ 
tion to the other through the hori¬ 
zontal, instead of through the ver¬ 
tical, as in the fan fold. In repeated 
instances, and in many localities, in 
the Grenville rocks of northern New 
York, the writer has observed that 
change in dip has taken place 
through the vertical instead of 

through the horizontal, and this ° n the assumption of fan fold structure 

seems to imply a condition of very close folding in the Gren¬ 
ville rocks at many and widely distributed points. In this 
especial case the dips change from the northwest to the 
southeast through the vertical in the schists northeast of Mill- 
site lake, but with some comparatively flat dips in the inter- 
banded quartzites north of the lake. At the same time the schists 
become greatly contorted and puckered. Millsite lake seems to lie 
closely along the axis of the fold. The section shown in figure 9 
was sketched from an exposure mile northeast of Millsite lake. 




Fit? q Exposure of Grenville recks \ mile northeast of Millsite lake, showing sharply 
fnlded quartzite q-q with a pinched in thin, limestone between the quartzite limbs, 1, the 
quartzite sueSded on the left by hornblende schists, s, and very schistose mica schist 
ms, the dip being vertical or nearly so throughout 





















112 


NEW YORK STATE MUSEUM 


The structure here is definitely anticlinal, though that is no indica¬ 
tion of similar structure in the main fold, since minor folds on 
its flanks must consist of both anticlines and synclines. It will 
serve, however, as a sample of many similar exposures in the district 
which show clearly that the series is folded, and that it is closely 
folded. It also well illustrates the closely compressed conditions, 
steep dips, and minor folds which prevail in the vicinity of the 
axis of the supposed fold. 

The writer’s opinion is that the structure here presented is syn¬ 
clinal, similar to that depicted in figure 7. The discussion, how¬ 
ever, serves to present the lack of certainty which prevails, and the 
possibility that the structure is of precisely opposite character. 
Either one indicates folding, but one precisely reverses the order 
of rock succession of the other. 

It is also thought probable that the heavy quartzite along the 
axis of the supposed fold is the same stratum as the even more 
massive looking quartzite of Grindstone and Wellesley islands. If 
the structure be synclinal, as supposed, this quartzite is the youngest 
Grenville formation of the mapped district, but if anticlinal it is 
the oldest. If these two quartzite belts do represent lines of out¬ 
crop of the same quartzite formation, there should be an addi¬ 
tional line of outcrop of the thick limestone somewhere between the 
two, in the near vicinity of the river. This does not appear but 
its absence is not a fatal objection to this interpretation of the 
structure, since the Grenville rocks there have been completely cut 
out by the granite of the Alexandria bathylith, and it is impossible 
to say what may have originally been there. 

In summation it may be said that the Grenville rocks are greatly 
tilted, suggesting strongly compressive folding, and frequent small 
folds occur. Two belts of thick limestone and two of thick quart¬ 
zite suggest a single formation of each in folded condition. Study 
of the dips suggests that this folding is of a certain type, but it is 
possible that, owing to very intense compression, the structure is 
just the reverse of that suggested. It has not proved possible to 
determine the order of succession of the various formations com¬ 
posing the Grenville, and to use that succession as the key for un¬ 
raveling the structure, as is the usual method in folded rocks. 
Instead the attempt has been made to decipher the structure and 
from that to determine the order of succession, but with only 
indifferent success. 

Paleozoic folding. While the Paleozoic rocks of the district 
show but a trifling amount of folding, it is of interesting nature 


GEOLOGY OF THOUSAND ISLANDS REGION II 3 

and to a certain extent at least is due to the pivotal situation of the 
region with respect to the early Paleozoic warpings, as has already 
been shown. In general the rocks lie, in nearly flat attitude, on the 
worn surface of the sharply folded Precambric rocks. Over most 
of the district a low, southwesterly dip prevails; locally, however, 
the dip steepens to 5 0 or more, and dips occur in all compass direc¬ 
tions. A strong westerly dip in the rocks along the Black river 
just above the bridge at Brownville is well shown in plate 28, and 
the dip is to the north, into the bank, as well, rock layers on the 
south side of the river lying some 10 feet higher than their 
equivalents on the north bank. In plate 24 a rather steep north¬ 
erly dip in the Black River limestone at Watertown is shown, and 
in plate 21 a similar easterly dip in the same formation at another 
locality. These are samples of what is a matter of common oc¬ 
currence all over the district. The areal mapping plainly brings 
out the presence of a series of folds which trend somewhat to the 
east of north. It also shows that the present stream valleys of the 
region in large part trend with these folds and chiefly follow the 
anticlines, while the synclines constitute the higher ground be¬ 
tween. 1 Examples are the valleys running south from Theresa and 
from Evans Mills on the Theresa sheet; the French creek valley 
and the Chaumont valley on the Clayton sheet; and the Clear lake- 
Butterfield lake-Black creek valley on the Alexandria sheet; but 
there are many others of minor importance. 

In addition to these nearly north-south folds there is a second 
set, about at right angles to the first, trending somewhat to the 
north of west, in parallelism with the Frontenac axis which is 
itself a fold of this group, the axial and most prominent one. 
Though mostly of minor importance, these folds are likely earlier 
than the others, and in part at least owe their existence to the 
warpings and tiltings of the region in early Paleozoic times, when 
it oscillated up and down, with tipping now to the east and now 
to the west. The Frontenac axis appears to b.e the major warp 
of this seres, and the others are minor corrugations, grouped 
about it and diminishing in importance with recession from it. 

1 An anticline is the upward folding of rock layers into a long and rela¬ 
tively narrow arch; a syncline, the downfolding into a similar trough. 
Where erosion has removed the upper portion of such folds a worn off 
anticline is readily recognized on an areal map since it will show an older 
mck centrally,- followed by successively younger rocks in the same order on 
each side; while an eroded syncline will show a younver rock in the center, 
followed by successively older rocks on each side. . Thus the French creek 
valley, south of Clayton, shows Precambric rocks centrally, adjoined by 
Potsdam on each side, Potsdam adjoined by Theresa and' that by Pamelia 
limestone, and the structure there is anticlinal. 



1 14 NEW YORK STATE MUSEUM 

In addition to the evidence which the general stratigraphy of the 
region furnishes as to the early date of some of this warping, evi¬ 
dence which has been already set forth, it also appears that the 
Potsdam and Theresa formations are somewhat more folded than 
are the overlying limestones, implying that they were somewhat 
folded prior to the deposition of the limestones. This is best 
shown in the district southwest from Clayton, along the valley of 
French creek, where the Potsdam is arched up into a prominent 
dome, even to the extent of bringing up the Precambric. The 
dome falls away to the south with rather steep dip, there is scant 
room for the Theresa formation between the south margin of Pots¬ 
dam outcrop and the Pamelia front just beyond, and this Pamelia 
inface passes across the line of prolongation of this fold to the 
south yet shows no sign of being affected by it, being precisely 
the same cliff of horizontal limestone that it is to the east and 
west of this line. It is of course possible that a fault lies between, 
but the faults of the district are infrequent and insignificant, so far 
as known, so that the supposition seems unlikely, and the evidence 
seems to clearly point to folding and subsequent wear, during the 
long time interval between the close of Theresa and the beginning of 
Pamelia deposition. Evidence of less distinctive character but of 
the same kind is also forthcoming elsewhere. 

Two series of low folds intersecting at right angles result in pro¬ 
ducing maxima of elevation at the intersections of arches and of 
depression at trough intersections, with intermediate conditions 
where trough of one set meets arch of the other. In other words 
the axes of the north-south folds are themselves folded by the east- 
west folds, producing elevated domes along the arches, and depressed 
basins along the troughs. A prominent feature of the areal maps is 
the considerable number of outliers and inkers of the various forma¬ 
tions there shown. 1 The abundant Potsdam outliers on the Pre¬ 
cambric are more largely due to the irregularity of the floor on which 
the formation was laid down, than to the .subsequent folding. But 

1 Along the southern margin of the Theresa sheet are shown a number 
of patches of Leray limestone, lying to the north of the main line of 
outcrop of the formation, and entirely surrounded by the older Lowville 
limestone. The Leray limestone formerly extended over the entire dis¬ 
trict, and has been worn away from much of it, these representing out- 
lving patches or residuals left behind in this general process of removal 
hence known as outliers. Inkers on the other hand are patches of an older 
rock entirely surrounded by a younger, such as the Precambric by French 
CF ^i -d SOU ^ Ciayton, or the Lowville near Threemile Bay and Three- 
mne Bay creek, on the Clayton sheet. These are much less common than 
outliers and are strongly indicative of a warped upper surface of the 
formation constituting the inlier. 



Plate 28 



Lowville limestone, capped by Leray limestone, at Brownville, extreme southwest corner of Theresa 
quadrangle. View looking northeasterly, across the Black river and upstream, showing the westerly 
limb of one of the low folds which characterize the Paleozoic rocks. The water is slack water, back of 
a dam, hence the river surface is horizontal. H. P. Cushing, photo, 1908 










GEOLOGY OF THOUSAND ISLANDS REGION 


115 


in the case of the other formations the great majority of the out¬ 
liers are owing to wear on rocks of this folded type. The numerous 
outliers of Leray limestone on the Theresa and Clayton sheets 
chiefly mark the positions of basins (points of intersection of 
synclines of both series of folds), the dips being everywhere in 
toward the center. Similarly the Lowville inkers which Ruedemann 
has mapped on the Clayton sheet, north of Threemile and Guffin 
bays, mark the summit of domes (intersections of anticlines) with 
dip outwardly from the center. In the case of some of the outliers 
however, those of the Theresa formation on the Potsdam west of 
Theresa for example, the dome structure instead of the basin struc¬ 
ture is exhibited, the outlier showing no prominent inface, and with 
dip outward from the center. The domed structure often shows 
excellently elsewhere, as for example in the Theresa formation at 
Orleans Four Corners (Theresa sheet) where the upper surface of 
a single massive layer of the formation protudes above the soil as a 
low, shallow dome, dipping outwardly in all directions. Many other 
examples might be cited and, owing to the abundance of rock ex¬ 
posures in the district the evidence of these structures is unusually 
clear, and it is quite certain that these, two sets of low, cross folds 
occur. 

Postglacial folds. There are in the district at least a half 
dozen examples of low folds, or buckles, of the surface rocks, which 
are of very recent origin. Though they form only a minor struc¬ 
tural and topographic feature, they are rather unusual and the in¬ 
terest attaching to them is out of all proportion to their size and 
frequency. The writer has noted three of them in the limestones, 
Lowville and Pamelia, and Professor Fairchild has called his atten¬ 
tion to two others. In addition at least one occurs in the Potsdam 
sandstone. The limestone folds seem all to conform to a common 
type so that a description of one of them, and of the one in the 
Potsdam, will answer every purpose. 

The Potsdam fold occurs 2 miles south of Chippewa Bay, in the 
northeastern portion of the Alexandria sheet, is near the roadside 
and easily visible from it. It is 40 yards long, trends n. 28° w., and 
a view of it, taken at the south end, appears in plate 29. It rises 
sharply from the surface of an extensive plain, underlaid by nearly 
horizontal sandstone, with but a scanty soil covering and much bare 
rock exposed. The fold is of bared rock with beautifully glaciated 
surface, whose striations demonstrate that the buckling has Occurred 
since the glaciation. The central portion is buckled up about 12 feet. 
The photograph clearly shows that, owing to compression, the rocks 


ii 6 


NEW YORK STATE MUSEUM 


were bent upward until, the elastic limit being exceeded, the fold 
snapped along the crest, furnishing relief to the bent flanks and per¬ 
mitting them to straighten. In the rock here only a single set of 
good joints appears, and this runs at right angles to the axis of the 
fold separating it into a series of transverse blocks. On bending, 
these seem to have fractured individually instead of collectively, so 
that the axial fracture does not coincide in the different blocks, but 
departs from the median line, now on one side and again on the 
other, as illustrated in figure io, giving rise to the dovetailing of 
slabs along the crest, so well shown in the photograph. 


• • • 

J J J 



Fig. io Plan of fold in Potsdam sandstone, j-j-j=joints; f-f=fracture along crest, illus¬ 
trating the manner in which the fracture shifts laterally in the different joint blocks, caus¬ 
ing overlap of the rock edges along the crest. 

One view of one of the folds in the Lowville limestone is shown 
in plate 30. The greater part of this fold is covered with soil, but 
centrally it has been stripped and a small amount of rock removed 
for local use. It seems to have about the same length as the previous 
one, and to be buckled up about the same amount. Its axis trends 
to the northwest. The rock is more closely jointed than in the Pots¬ 
dam fold, and with two good sets present, one of which trends north¬ 
west with the fold, as the view clearly shows. Fracture then was 
unnecessary in this case and readjustment took place by utilization 
of these northwest joints, and instead of being actually folded, as 
might be judged from the photographs, the displacement really has 
the character shown in figure 11, as sketched on the spot. 



Fig. 11 Diagram to illustrate the arrangement of the joint blocks in the Lowville fold 
shown in plate 30 The central block lies nearly horizontally, the adjacent ones tipped in 
the directions and by the amounts indicated. 

Small postglacial folds of similar type have been described by a 
number of authors and from various localities, and they have re¬ 
sulted from several different causes. Gilbert, after seeing some of 




















Plate 29 



Postglacial _ arch in Potsdam sandstone, 2 miles south of Chippewa Bay, Alexandria quadrangle. The 
rock surface is glacially polished and shows the later date of the arching. The ruptured crest, and the 
dovetailing of slabs along the crest are also shown., and the set of cross joints. H. P. Cushing, photo 
















































• -• 






















































Plate 30 





Postglacial fold in Lowville limestone, 1 mile west of Sanford. Corners, Theresa quadrangle, looking northwest. 
The prolongation of the arch under cover as a topographic ridge is also shown. PI. P. Cushing, photo, 1907 















GEOLOGY OF THOUSAND ISLANDS REGION 


II7 


the limestone folds in this district, as well as others in shales in 
western New York and Ohio, demonstrated that they were super¬ 
ficial and postglacial, and attributed them to “ horizontal expansion 
of superficial strata, consequent on postglacial amelioration of cli¬ 
mate.’’ 1 Idle writer does not question the correctness of this ex¬ 
planation as applied to the folds in shales and shaly rocks, which 
Gilbert describes, but is not so sure as to its adequacy in the case of 
quite massive, rigid limestones such as the Lowville, and is especially 
doubtful of it as applied to a well cemented, massive sandstone like 
the Potsdam, which is an exceedingly rigid and resistant rock. Post¬ 
glacial climate is no warmer than was preglacial climate. Unless 
therefore the weight of the overlying ice was sufficient to cause some 
lateral spreading of the rocks, at the same time that it was producing 
contraction in them by lowering of their temperature, postglacial 
warming would merely reexpand them to their 'preglacial condition. 
There is no question as to the competency of the ice weight to pro¬ 
duce lateral spread in shales and shaly rocks. Many shales are 
known to spread and to give rise to buckles under much smaller 
pressures, hence the cause suggested by Gilbert would seem ample 
to account for the results. But the pressure necessary to produce 
spread in a massive, rigid limestone is quite another matter, and that 
required in the case of such a rock as the Potsdam sandstone is of 
a still higher order. The weight of an ice sheet i mile thick would 
be equal to that of from 1700 to 1800 feet of average sedimentary 
rock. We do not know the thickness which the ice attained over this 
region but even the supposition that it was much more than a mile 
thick does not greatly enhance our figures of rock thickness. Are 
such pressures, even if applied continuously for a long time, suffi¬ 
cient to bring about lateral spreading in such a rock as the Potsdam? 
So far as known to the writer there are no direct, positive data 
which warrant a definite answer to this question. It is certain, how¬ 
ever, that at such depths below the surface such rocks are abundantly 
fissured, are often porous, and permit free passage of fluids. This 
certainly suggests that they are not under sufficient weight to close 
up cracks. 

If. however, this pressure due to the ice load could be rein¬ 
forced by pressure from some other source in sufficient amount, 
the necessary lateral spreading could be brought about. A 

1 Gilbert, G. K. Am. Ass’n Adv. Sci. Proc. 35-227; 40:249. 

Am. Jour. Soi. ser. 3, 32:324. . > _■ 

The writer is under great obligations to Dr G. K. Gilbert, J. C. Branner 
and H. F. Reid for references to the literature and for personal discussion 
of these folds. 



n8 


NEW YORK STATE MUSEUM 


very likely source of such additional pressure is to be found in 
the well known oscillations of level which the district has under¬ 
gone preceding, during and since glaciation. The general dis¬ 
trict has increased its altitude by some 400 feet since the ice dis¬ 
appeared from the St Lawrence valley, and this change is simply 
the last of a series of oscillations. Furthermore these move¬ 
ments were of the nature of warps, the changes in level not being 
everywhere the same, but of varying amount. Such warping 
must bring about compression in some tracts and stretching in 
others. The contraction produced in the rocks by the cooling of 
the ice sheet would likely have manifested itself in mere slight 
widening along the joint cracks, and side compression brought 
about by warping may have sufficed locally to close up these 
widened joints. In such case postglacial increase of tempera¬ 
ture might well tend to cause buckling of the rocks. The warp¬ 
ing is of such nature that it would tend to produce thrust from 
the northeast, and it is to be noted that these folds trend north¬ 
west, as should be the case on this hypothesis. 

There at once arises, however, the further question as to 
whether the compression consequent upon warping may not 
have been perfectly competent to cause the buckling, entirely 
independently of any effect which the ice may have had, and 
this seems to the writer very probable. Dr Reid, in correspond¬ 
ence, states his belief that “ we must fall back on the general 
explanation that movements of the crust are in progress which 
have produced these bucklings.” Dr Branner expresses similar 
views. In any case, until it has been shown that lateral spread¬ 
ing may be produced in rocks of this resistant type by load no 
greater than that of the ice sheet, some doubt must attach to the 
competency of Gilbert’s hypothesis as applied to these special cases. 

Faults 

Faults of considerable magnitude and importance have not 
been noted in the district, and the fairly accurate areal mapping 
which the abundant rock exposures render possible, indicates 
that no such are present, at least in the Paleozoic rocks. Small 
faults appear, however, in considerable number in all the rocks 
and are apparently of different age. 

In the Precambric rocks. Small faults, with dislocations of 
from a fraction of an inch to a few feet occur in a great number 
of localities in the Precambric rocks, as already pointed out by 


GEOLOGY OF THOUSAND ISLANDS REGION II 9 

Smyth. 1 1 he numerous dikes, chiefly of granite, which every¬ 
where cut the Grenville give every facility for determining their 
presence. They are in great number but for the most part of 
very trifling displacement. Similar faulting locally in the 
Paleozoic rocks suggests that this faulting is of Paleozoic date, 
but the much greater number of faults noted in the older rocks 
indicates some Precambric faulting at least, and of this there is 
direct evidence in some instances. The hand specimen shown in 
plate 5, lower figure, presents an adequate illustration. The rock is a 
well banded, acid Grenville gneiss, consisting chiefly of feldspar and 
quartz and seems certainly a sediment, a metamorphosed shaly sand¬ 
stone. The bands vary in color from a light reddish to a black¬ 
ish red, and are very plain, though without sufficient contrast to 
photograph clearly. They are parallel to the bedding and seem 
certainly to represent original lamination in the rock. Shearing 
has occurred, with development of fracture cleavage, principally 
at a high angle with the bedding, but with secondary fractures 
which rudely follow it, and along many of the former minute 
slips of the rock have taken place. These old cracks are now 
solidly welded up with secondary minerals, black in color, except 
for an occasional, shining pyrite crystal, and it is this secondary 
filling which furnishes the evidence for the date of the deforma¬ 
tion and gives the chief interest to the rock. Pyroxene, horn¬ 
blende and black mica (biotite), stated in order of abundance, 
are the minerals composing the filling, their grain somewhat 
coarser than that of the rock. They are of the same types as the 
minerals of the Grenville green schists. They argue for fairly 
deep seated conditions at the time of the deformation. The 
fractures show that the rock was above the zone of flow, but the 
minerals, the pyroxene especially, indicate anamorphic condi¬ 
tions and point to deformation in the lower part of the zone of 
fracture. Such faulting seems not only of Precambric date, but 
to have preceded the greater part of the long, Precambric erosion 
interval. Its date is made quite certain by the numerous dikes 
of Picton granite which cut the schists, the granite being younger 
than the filling of the shear zones. 

There are also frequent shear zones in the Precambric rocks, 
zones of no great breadth but of considerable linear extent, along 
which the rock is shattered into quite small blocks by a multitude 
of close spaced joints, and along which some faulting has cer¬ 
tainly taken place, small slips along many planes. No such shear 


1 N. Y. State Geol. 19th An. Rep’t, pi. 15. 



120 


NEW YORK STATE MUSEUM 


zones have been noted in the Paleozoic rocks, and the deforma¬ 
tion which gave rise to them seems certainly of Precambric date, 
though later than that previously described since the rocks were 
under less load, hence nearer the surface. 

In the Paleozoic rocks. Frequent faults of small throw may be 
made out in the Potsdam sandstone. The red and white banded 
stone which constitutes the lower part of the formation on the 
Alexandria quadrangle is excellently adapted to display them, 
and a magnificent exhibit of them is given on the bare rock surface 
of the large Potsdam outlier which lies between the railroad and the 
north end of Butterfield lake. Here over a considerable area the 
faults are spaced but a few feet apart, and though the throw seldom 
amounts to as much as a foot, and is frequently only a fraction of 
an inch, the combined displacement of the whole must be quite con¬ 
siderable, as there are hundreds of them. For a hand specimen from 
this locality, showing one of these faults see plate 31, upper figure. 
All noted are normal faults of slight hade. The fault planes are 
filled with sand grains in all respects like those of the rock itself and 
as thoroughly cemented, which would seem to indicate that the 
faulting occurred before rock cementation was far advanced, so that 
the grains gave way individually instead of as sandstone fragments, 
whereas the latter would certainly be the method were faulting to 
take place in the rock now. Cementation subsequent to the faulting 
has thoroughly indurated the whole. 

The bulk of the formation is rather uniformly colored and 
hence not so well adapted to display faulting of this type, and it 
is not certain whether it occurs in it or not. 

There are also occasional small faults of a later type in the 
Potsdam, the fault planes remaining as open cracks, with sand¬ 
stone fragments in the fault breccias. A small fault of this type 
appears in plate 12. 

In the limestones a few faults have been noted whose throw 
amounts to several feet. The best example seen by the writer 
is in the lower Pamelia limestones of the Pamelia inface, 2 miles 
east of Perch lake. The section here shows the basal, black, 
fossiliferous limestones, overlaid by a thickness of some 15 feet of 
thin bedded, earthy limestone, followed in its turn by massive 
blue limestone with interbedded gray magnesian layers. These 
upper massive limestones are faulted down against the earthy 
limestone, the fault bearing n. 30° e, downthrowing to the east 
and with a throw of some 20 feet. 


Plate 31 




Upper figure. Hand specimen of faulted Potsdam sandstone, nearly 
natural size. The rock is red, with white streaks, and the fault plane is 
filled with white, thoroughly cemented sand. 

Lower figure. Hand specimen of basal, Lowville conglomerate from 
near Depauville (Clayton quadrangle). The pebbles of fine limestone 
mud, of dove color, weather prominently white, as compared with the 
remainder of the rock surface. H. P. Cushing, photo 





















. 

























































































































































































GEOLOGY OF THOUSAND ISLANDS REGION 121 

Kueclemann has mapped two small faults on the Clayton and 
Cape Vincent sheets and furnishes the following description: 

In Chaumont village (Clayton sheet) is a small outlier of Tren¬ 
ton limestone, immediately to the west of which, and at the same 
level, is W atertown limestone. The relations are best seen 
about the viaduct on the Depauville road and along the railway 
immediately to the east. Under the viaduct is Watertown 
limestone. Along the railroad is Trenton at the same level, 
with a cut which shows steeply dipping Trenton, the dip being 
away from the Watertown and apparently due to drag on the 
downthrow side of a fault. The fault downthrows to the east, 
with a throw just sufficient to preserve the small patch of Tren¬ 
ton on the downthrow side. Its trend is substantially parallel to 
the road, or about northeast. 

On Carleton island (Cape Vincent sheet} the presence of a 
fault cutting off the small western promontory, which consists of 
W atertown limestone, is suggested by the depression which 
separates the promontory from the mainland, within which no 
rock shows, and which is faced by a rock cliff on each side, a high 
Trenton cliff on the main island side and a lower cliff of Water- 
town on the other. A small fault along the depression, with down¬ 
throw to the east, is thus indicated. 

TOPOGRAPHYi 

The present day topography is the result of erosional forces act¬ 
ing for long ages upon a land surface, which from time to time 
varied in altitude and which underwent climatic changes. The char¬ 
acter of the erosion, and of the resultant topography are also con¬ 
ditioned upon the character, attitude and structure of the rocks 
comprising the region. We have some slight knowledge of the 
changes in altitude of the region. The climate has certainly varied 
much, both in respect to temperature and to humidity, with, in quite 
recent times, the climatic rigor of the glacial period. The erosional 
forces, as always, have been in part atmospheric, but chiefly those 
of moving water and ice. 

During paleozoic times the region was, when not submerged, one 
of low altitude. It was uplifted somewhat at the close of the Paleo¬ 
zoic, and during Mesozoic time seems to have been worn down to a 
comparatively even surface of low altitude, in common with much 
of the eastern portion of the continent. During the succeeding Ter¬ 
tiary it participated in the general uplift of the same region, and its 
present relief is chiefly a product of Tertiary wear. 


1 By H. P. Cushing. 



122 


NEW YORK STATE MUSEUM 


Paleozoic altitude and climate 

During the Lower Siluric the immediate region was from time 
to time submerged, at other times was above sea level. During 
submergence there were neighboring lands. It is apparent that all 
were of low altitude. During emergence there was but trifling wear 
on the exposed land surface. During submergence the adjacent 
lands furnished but little land wash, though the Precambric rocks 
of which they were formed were capable of supplying great quanti¬ 
ties of sand and mud under conditions of any freedom of drainage', 
and they were near at hand and of much extent. A small thickness 
of sand marks the horizon of the Pamelia-Lowville break, others 
wise the formations are unbroken limestone, until the shales of the 
upper division come in; and these are more indicative of stronger 
currents in the marine waters, than of especially increased altitudes 
of the neighboring lands. The succeeding Oswego sandstone seems 
a continental, rather than a marine deposit and indicates freer 
drainage and somewhat greater altitude. 

But little has been gleaned from the region itself as to climatic 
oscillations in these early times. The upper Pamelia was marked 
by a somewhat arid, and perhaps warm climate, as has been seen. 
Probably the same was true of the Oswego-Medina, though that lies 
outside our district. The Potsdam climate is a puzzle. Farther 
east, where the basal Potsdam consists largely of arkose, and where 
the Precambric underneath shows the same freshness and the same 
irregularity of surface under the Potsdam that it does here, we 
have expressed the opinion that the sandstone was a continental de¬ 
posit, so far as the basal portion is concerned, and that the climate 
was arid. Flere however, with the same character of floor, we have 
a pure sand deposit, instead of arkose. The unweathered character 
of the Precambric rocks, the absence of residual weathered material, 
except in very scanty amount in the most sheltered situations, 
and the general base-leveled character of the surface, seem to 
point to long continued wear under conditions of aridity and 
removal of disintegrated material by the wind. Under those 
circumstances however the residual products should be arkose, in¬ 
stead of pure quartz sand such as constitutes the Potsdam here. 
There is much more feldspar in the basal Pamelia sand than in 
the Potsdam, and even in that it is not in great quantity. We are 
unable to correlate this quartz sand with conditions of climatic arid¬ 
ity, and equally unable to explain the character of the Precambric 
surface, and the unweathered condition of the rocks, satisfactorily 
to ourselves, on any other basis. 


GEOLOGY OF THOUSAND ISLANDS REGION 


123 


During the remainder of the Paleozoic we know but little concern¬ 
ing the region here, except by comparison with other regions more 
or less remote from it. It may have been somewhat submerged dur¬ 
ing the Siluric, but certainly, for most of the time, it was a land 
area, and the small amount of wear which it experienced indicates 
that, for most of the time, its altitude was low. 

Amount of erosion 

The total amount of rock thickness which has been worn away 
since the region became a land area, can not of course be exactly 
determined, though it is thought that it can be approximated. To 
the south the Trenton limestone is overlaid by the Utica and Lor¬ 
raine shales, and these by the Oswego sandstone and Medina shale 
and sandstone. These are ail sufficiently near to make it in high 
degree probable that they were laid down over our district, espe¬ 
cially since the source of their sediment must have been to the north 
and east. It is regarded as unlikely that they had any greater thick¬ 
ness here than they now show toward the south, but they may have 
been as thick. We have no evidence that any formations later than 
the Medina were ever deposited here, and even if so, the thickness 
would seem to have been small and the submergence brief. If 
therefore we allow to these formations the full thickness which they 
show to the south, we are likely exaggerating their thickness here 
and allowing a margin to account for any possible later formations 
which may have existed. 

The deep wells which have been drilled at various points between 
this district and the Syracuse region, give the data desired. In the 
Monroe well at Baldwinsville the drill went through 1740 feet of 
sandstone (Medina-Oswego) and shale (Lorraine-Utica), reaching 
the top of the Trenton at 2240 feet. If we assume them to have 
been deposited over our district in the same thickness, and add the 
thickness of underlying rock (Potsdam-Trenton) we get 2600 feet 
as an outside measurement of the Paleozoic thickness here origi¬ 
nally. In all probability this is considerably too high. There were 
1200 feet of sandstone and 500 feet of shale above the Trenton in 
this well, and the full thickness of both was passed through by the 
drill. In the wells further north, as in Orwell and Central Square, 
less sandstone appears but the shales thicken to 700 feet. Since, 
no certainty is possible our purpose is best subserved by a generous 
estimate, and an original thickness of 3000 feet of Paleozoic rocks 
here will be assumed. Where Precambric rocks are now at the 
surface, 3000 feet is regarded as the outside limit of the thickness 


124 


NEW YORK STATE MUSEUM 


of overlying rock which has heen worn away, from the close of 
the Siluric to the present. Where the various members of the 
Paleozoic form the surface rocks, erosion is correspondingly less, 
and since the Precambric is at the surface over but a small fraction 
of the region, the general erosion has been less than that figure. 
Considering the great length of time involved, this represents no 
great erosion, and seems to point to land of no great altitude for 
much of the time. It seems to be further demonstrable that at least 
one half of this erosion took place in Tertiary time, which argues 
all the more strongly for general low altitude during the preceding 
ages of the Mesozoic and later Paleozoic. 

Original drainage 

As uplifted at the close of the Siluric, and following the deposi¬ 
tion of the Oswego sandstone, our area became the marginal portion 
of land masses to the north and the east, and in all probability 
possessed a gentle slope to the southwest. The original streams 
must have followed down this slope to the margins of the later 
Paleozoic water bodies of central New York, thus flowing in the 
direction of the rock dip, and at right angles to the strike. Having 
taken position they would commence to carve valleys, whose possi¬ 
ble depth would depend upon the altitude of the land. Streams of 
this type are called consequent streams. With valley cutting in 
progress, tributaries to these original streams commence to develop, 
beginning as gullies in the valley sides, and steadily cutting head- 
wards. Obviously they form most readily where the valley walls are 
weakest, and tend to remain in the weak rock belts, following their 
strike, hence with courses which make substantially a right angle 
with those of the original streams. Such streams are called subse¬ 
quent, since their development must wait on that of the consequent 
streams. With a belt of weak rocks to follow, these subsequent 
streams may eventually become the chief streams of a region, divert¬ 
ing or “ capturing ” the headwaters of the old consequent streams. 
The Utica and Lorraine shales constitute such a weak rock belt in 
this region, with the great Ontario valley eaten out along it, the 
■ Adirondack highland blocking its extension further east. 

With chiefly low lands, drainage adjustments would go on 
but slowly, and the drainage may have been considerably modified 
from time to time by tilting of the land, under these low altitude 
conditions. With the passage of time, however, it has come about 
that the chief streams of the region are now in subsequent position, 



GEOLOGY OF THOUSAND ISLANDS REGION 1 25 

and there is little trace of the old consequent streams, though the 
streams running westerly, out of the Adirondacks, seem to repre¬ 
sent the old heads of such streams. 

Tertiary uplift 

Evidence derived chiefly from without the district indicates that 
our region, in common with much of eastern North America, was 
worn down to a comparatively smooth surface (peneplain) of low 
altitude by the close of Mesozoic time. It then experienced con¬ 
siderable uplift, erosion was renewed and streams cut and widened 
considerable valleys in the weaker rock belts, while the more 
resistant rocks retained in considerable measure their original alti¬ 
tude, and give us the remnants of the old plain. Elevations of over 
1500 feet are found on the Watertown sheet, immediately south 
of our map. On the Port Leyden sheet, next south, the altitudes 
reach almost 2000 feet, the district there forming a low plateau, 
capped by the resistant Oswego sandstone, between the Ontario low¬ 
land to the west and the broad valley of the Black river to the 
east. East of the valley the levels rise within a few miles to 2000 
feet, in the westerly edge of the Adirondack platform, and from 
there continue to slowly rise eastward. The Adirondack highland, 
and the Oswego sandstone plateau, are regarded as remnants of the 
old peneplain surface, which as uplifted, was given a slight tilt 
toward the west, while the deep valleys of the region have been cut 
since the uplift and give some measure of its amount. Unless later 
rocks in considerable thickness have been worn away from the 
surface of the Oswego sandstone plateau, the amount of wear 
there has been very slight; yet this small thickness of removed rock 
represents the general erosion over the entire region from the close 
of the Ordovicic to the close of the Cretaceous, a wear so slight 
as to be only compatible with low altitude of land when the length 
of the time interval is considered. 

Tertiary drainage 

The Tertiary uplift of the region gave to the land an altitude 
in excess of that of the present. . A partial measure of this ex¬ 
cess is the difference in level between the Tertiary valley bottoms 
and those of today; but we do not know the depth of valley filling 
in this district and hence can not state the excess. Even before 
the uplift the streams had likely become adjusted to much their 
present relation, namely consequent streams flowing westerly 



126 NEW YORK STATE MUSEUM 

and northwesterly out of the Adirondack reg'ion, and southerly 
and southwesterly out of the Canadian Precambric region, and 
these streams diverted by the large subsequent streams in the 
Black river, St Lawrence and Ontario valleys; the Black along 
the overlap of the sedimentaries on the crystallines, the Ontario 
valley on the thick shales, and the St Lawrence on the limestones 
of the depressed trough, with bordering Potsdam and Precambric 
on both sides; hence each on a relatively weak rock belt. In 
these positions the Tertiary successors dug out their valleys. 
They mostly flowed as they do now, the important exception be¬ 
ing in the case of the Ontario-St Lawrence drainage.. The fold, 
or warp, of the Frontenac axis crosses this drainage line in our 
district. Even before being worn down to the Precambric this 
would make a natural rock barrier to the drainage, since the 
lower Ordovicic rocks are more resistant than the upper, and 
hence form a divide or col between waters flowing northeast, 
down the present St Lawrence valley, and waters passing west 
through the Ontario valley, the Black river forming the chief 
stream of the immediate region, as it now does. All writers on 
the district have considered that, in Tertiary times, the Black 
river turned westward into the Ontario valley. Wilson espe¬ 
cially has considered the drainage of the immediate region in 
some detail in a most excellent paper, with much of which we 
are in entire agreement. 1 He points out that the St Lawrence 
lacks a definite channel in the Thousand Island region, going 
over the Frontenac axis at its most depressed point. With this 
we agree, but we do not coincide with his view that the Black 
river, in its course across the mapped area, is closely in its 
preglacial channel (the river below Carthage is here referred 
to). We are however in doubt as to where this preglacial chan¬ 
nel was. Fairchild disagrees entirely with the view that the 
preglacial waters of the Black river went westward, and turns 
them into the St Lawrence valley below the col. His views are 
presented on pages 141-145. I dissent somewhat, preferring the 
view that the drainage went into the Ontario basin, but must 
frankly admit that I have not discovered the precise route fol¬ 
lowed, so that it seems to me that opinion in the matter must 
be held in abeyance, pending discovery of the actual old channel. 

If the Frontenac axis formed a divide here in Tertiary times 
such divide should run across our district toward the Adiron- 
dacks, as a divide between streams going north and those moving 


1 Geol. Soc. Am. Bui. 15:236-42. 



GEOLOGY OF THOUSAND ISLANDS REGION 


127 


west. The presence of this divide, with its sharply cut ravines 
heading against it on both sides is to us one of the most interest¬ 
ing features of our district. It is most unfortunate that the maps 
of the quadrangles next east are not available so that it could 
be further traced in that direction. Inspection of the Alexandria 
and Theresa maps will show plainly its course across them. In 
the low grounds near the St Lawrence the ravine heads are not 
prominent, though the two lateral ravines into Cranberry creek 
valley from the east are good examples. But at Browns Corners, 
4 miles southeast of Alexandria Bay, is seen the head of the first 
of a series of sharply cut valley heads with northeast trend. The 
next is at Plessis, dropping down sharply into the Clear lake-Mud 
lake-Butterfield lake valley, with a secondary sharp drop at the 
head of Butterfield lake. One and one half miles southeast of 
Plessis, on the extreme south margin of the Alexandria sheet, 
is the head of the Hyde lake-Hyde creek-Perch river valley, on 
the other side of the divide, belonging to the southwest drainage. 
Just east are two sharply cut ravines heading on opposite sides 
cf a low pass across the divide, the valley of Crystal lake, which 
is tributary to the Mud lake valley, and the valley without pres¬ 
ent drainage, followed by the railroad and leading south into the 
Indian river valley on the Theresa sheet. This valley is some¬ 
what more blocked by drift than the others and seems to have 
held a shallow lake. The Millsite lake and Sixberry lake valleys 
also head sharply against the divide on the north. They are 
however of somewhat abnormal type. Most of the other valleys 
mentioned commence as distinct but shallow, rock-cut trenches, 
which, after a short course, suddenly deepen to gorges with walls 
from 40 to 100 feet high. The Clear lake and Hyde lake valleys 
nicely illustrate this type. The lakes are at the heads of long 
valleys leading away from the divide. The Crystal lake, Six- 
berry lake and Millsite lake valleys, on the other hand are short 
valleys, tributary to others at the side, and they deepen almost 
at once, instead of having the preliminary shallow course. The 
view of the head of Crystal lake valley [pi. 34] gives an excellent 
idea of the general character. 

Passing to the Theresa sheet, attention is at once directed to 
the considerable and deep valley, leading north past Theresa, the 
valley into which the modern Indian river breaks at that point, 
with production of falls and short gorge [pi. 32]. The valley it¬ 
self heads 3 miles further south. Two miles to the west is the 
Hyde creek-Perch river valley, running southwest and heading 


128 


NEW YORK STATE MUSEUM 


on the Alexandria sheet, as we have just seen. This parallel, 
but northerly-flowing Theresa valley plainly heads several miles 
south of the original line of the divide, in other words has 
pushed it south out of line by headward cutting of its valley. 
Its ability to do this was no doubt conditioned upon the weak 
resistance of the Grenville limestone belt there. Once the Pots¬ 
dam was cut through, rapid headward cutting of the stream would 
be possible. From the present valley head a shallow valley runs 
southwest to Perch lake, and it seems clear that formerly this 
valley headed along the old divide, and was diverted, bit by bit, 
by the more advantageously situated stream flowing the other 
way. The minor tributary valleys from the east and west, 
between Theresa and the north margin of the sheet, are southerly 
trending valleys, southeast or southwest, and hence adjusted to 
a southerly, rather than a northerly flowing stream. The north¬ 
erly flowing stream slowly captured and reversed the headwaters 
of the south stream, extending its capture through a distance of 
from 4 to 5 miles. 

Northeastward from Theresa are a number of valleys heading 
sharply against the Potsdam mass which there forms the divide, 
and leading away from it to the southwest. These are located on 
belts of Grenville limestone, or of weak schist, and therefore are 
broader and less ravinelike than most of such valleys in the dis¬ 
trict. They are, however, comparatively narrow, distinctly rock 
walled, and with present flat-bottomed floors owing to drift 
deposits. 

Here, in the northeast corner of the Theresa sheet, the divide 
runs off our maps to the east, and with maps of that district 
not yet available, its further course can not be traced. It, today, 
rises steadily in altitude in that direction, and is, as in Tertiary 
times, the divide between waters flowing north to the St Law¬ 
rence and west to the Ontario valley. 

The Indian river of today, from Theresa south to the great 
bend north of Evans Mills, is flowing in reversed direction 
through what was then the valley of a small stream heading 
near Theresa and flowing south. Wilson’s view is that at the 
bend it was tributary to a southwest stream, occupying the 
valley now followed by Indian river above the bend; and that 
their combined waters flowed south through the present West 
creek valley to the Black river. With our disbelief in the pres¬ 
ence of the Black river there at that time, coupled with the fact 
that the W.est creek valley seems both to widen, and to deepen, 


Plate 32 



The smaller of the two gateways at Theresa through which the Indian river passes into the preglacial 
valley. The rocks are steeply dipping Grenville schists. H. P. Cushing, photo, 1907 
















































' 









GEOLOGY OF THOUSAND ISLANDS REGION 1 29 

northward, we are in doubt as to the correctness of this view. 
Certain it is, however, that the present course of Indian river is 
a patchwork of various preglacial valleys, the modern character 
of the course being most excellently shown at Theresa where 
the river drops 80 feet, from a shallow valley into a much deeper 
one, entering this on its east side 3 miles below its valley head, 
with cutting of a short, postglacial gorge in the old valley 
side. 

Plateaus, terraces, scarps 

With the streams cutting down valleys and exposing rock 
formations of varying age and resistance in their valley walls, 
and with the slow widening of the valleys, the stronger rock 
beds of the region tend to outcrop in cliff form, the scarps run¬ 
ning across country in the direction of strike, and curving up 
the consequent valleys in the direction of dip. The stronger 
cliffs result where a more resistant rock overlies a considerably 
less resistant one, the more rapid wear of the underlying rock 
tending to keep a tolerably steep and precipitous cliff front. 
Where the differences in resistance are less, or where rapid 
changes in resistance occur, involving no great thickness of 
rock, low, subdued scarps are produced. 

Furthermore, where an overlying formation is weaker than that 
beneath, rapid wear is checked at the upper surface of the lower 
rock, the upper rock is stripped away from it and a flat bench of 
varying breadth is produced, separating the cliff fronts of the upper 
and lower formations. I11 the large way, ignoring minor complica¬ 
ting factors, the general topography of our district is of this type: 
flat platforms developed on the surfaces of the hard layers, and 
cliff fronts which mark the descent from one rock platform to the 
next, the cliff fronts facing toward the old land area, in this case to 
the north, hence often called in faces. 

The most prominent cliffs, and the broadest platforms of the dis¬ 
trict are those of the Potsdam sandstone, as it usually has consider¬ 
able thickness, is the strongest or most resistant of the Paleozoic 
rocks, and more enduring than much of the Precambric, on which it 
rests. The Precambric topography has already been described, and 
this does not need repetition. The Potsdam is thickest where the 
underlying Precambric is weakest, the bulk of the remaining Pots¬ 
dam rests on these weaker rocks, this being notably true in the case 
of the outliers. Potsdam cliffs from 20 to 60 feet high are abund¬ 
ant throughout the district, and are absent only where the under¬ 
lying rock is granite and the Potsdam very thin. Broad Potsdam 


130 


NEW YORK STATE MUSEUM 


platforms are well shown on both the Theresa arid Alexandria 
sheets. 

Though the Potsdam as a whole is strong, the uppermost beds, 
together with the sand beds in the basal Theresa, form a weak com¬ 
bination, in which the massive bed of the Potsdam summit is rela¬ 
tively strong. The overlying Theresa is also stronger than this weak 
zone, and hence the Theresa edges form rather prominent in faces, 
with these weak beds at their base; not infrequently also the strong 
summit bed of the Potsdam forms a narrow platform of its own, 
part way up the inface [pi. 33]. The Theresa rocks weather to 
iron stained crusts and their exposed edges have a thin bedded 
look, giving these infaces a peculiar and unmistakable look of 
their own. Above the base the Theresa shows rather rapid alter¬ 
nations of thicker and thinner bedded layers, the former somewhat 
more resistant, so that low infaces of these various layers are fre¬ 
quent throughout the Theresa country. 

The sandy basal layers of the Pamelia formation, some 25-30 feet 
thick, constitute the weakest zone within our map limits, and are 
readily stripped away from the Tribes Hill underneath, while the 
overlying limestone is more resistant, so it is not surprising that the 
Pamelia cliff front is one of the most conspicuous topographic fea¬ 
tures of the district, a feature which the contour maps clearly bring 
out. In front lies a flat Tribes Hill platform. The cliff ranges from 
20 feet to more than 100 feet in hight, but is usually from 50 to 60. 
Higher up in the formation the occasional very massive limestone 
beds form frequent low infaces of their own, as in the case of the 
Theresa formation. The Lowville differs but little from the Pamelia 
in resistance, and has no zone of weakness at its base, hence is not 
fronted by a prominent inface of its own, and is the only formation 
which lacks one. It has its own minor fronts, but these are of the 
same order of magnitude as those of the upper Pamelia beneath. 

The Leray is a thin formation, but because of the massive¬ 
ness of its beds, and the abundance of chert in its lower portion, it 
everywhere forms infaces with distinct characters of their own, of 
which the curious blocky type of weathering is the most conspicuous 
[pi. 20]. The 7 foot tier above also has a front of its own. 

The thin bedded Trenton limestone is considerably less resistant 
than the Watertown, hence the Watertown platform in front of the 
Trenton inface is comparatively broad, especially when the small 
thickness of the formation is taken into consideration. Notwith¬ 
standing the weakness of the Trenton, its inface to the south of 
the Black river is far the highest and most commanding of the 


Plate 33 



North face of Theresa escarpment, i l A miles southeast of Clayton, looking west. Theresa dolomite on left, 
upper surface of Potsdam sandstone on right and in foreground. H. P. Cushing, photo, 1908 

















GEOLOGY OF THOUSAND ISLANDS REGION I3I 

region. Only a little of this is within the map limits, in the ex¬ 
treme southeast portion of the Theresa quadrangle. Such Trenton 
as there is north of the river shows itself in rounded hills without 
prominent in face and this is its normal and usual character. The 
high cliff referred to is unusual and due to proximity to the Black 
river. 

Minor modifications of these general features are produced be¬ 
cause of the low folds of the Paleozoic rocks. The discussion of 
these has shown how low domes and shallow basins are thus pro¬ 
duced in the rocks, resulting in the formation of outliers and inliers 
of the various formations, with their local infacing or outfacing 
cliffs; resulting also in a lobation of the general formational in¬ 
facing fronts. As Ruedemann has stated these lobes are most con¬ 
spicuous in the Leray fronts, an additional cause being there 
at work to accentuate them. Nevertheless they are primarily due 
to the folding, the other infaces showing similar, even though less 
conspicuous lobes. The topographic maps show these general feat¬ 
ures excellently. 

The lowlands of our region today are chiefly the result of the 
stream wear during the Tertiary. The prominent rock infaces and 
platforms of the various formations are owing to the considerable 
differences in level between the low grounds and the adjacent up¬ 
lands, and terrace broadly the ascents from the one to the other. 
These features, together with those of the drainage outlined above, 
were substantially what they are now at the end of Tertiary time. 
There are few northern regions in which the general topography is 
so little changed, and has its Tertiary features so little masked by 
subsequent Pleistocene changes as is the case here. 

Lakes 

The group of lakes in the southeastern portion of the Alexandria 
quadrangle, together with a few more of the same type in the dis¬ 
trict to the eastward, constitute one of the very interesting features 
of the district. Their interest arises in part from their localization; 
they are abundant in this restricted area and are scarce or lacking 
elsewhere. In some features they resemble the much more abundant, 
and more widely dispersed, lakes of central Ontario, as described 
by Wilson; in one respect they are sharply contrasted with them. 

Wilson describes the Ontario district as characterized by a prom¬ 
inent cuesta front at the north edge of the Paleozoic limestones, 


132 


NEW YORK STATE MUSEUM 


overlooking the Precambric areas to the northward. The drainage 
is to the southwest and passes from the Precambric into the Paleo¬ 
zoic limestone country, the streams deeply notching the cuesta front 
as they pass into it. Of the lakes lie says: “In most cases the 
upper parts of these valleys, near where they pass through the 
cuesta front, form the basins of long, narrow lakes. The water 
seems in some cases to be held back by a drift dam, which partly 
blocks the lower part of the valley. Certainly in some cases, in all 
probability in most cases, the present lake basin is a rock basin 
and the existence of the present lake is due either to warping or 
possibly to differential erosion by ice. 1 ” 

In this district of Wilson’s the Potsdam and Theresa formations 
are absent, the Pamelia, or Lowville, resting on the Precambric, 
forming a single cuesta front that is more prominent than those in 
our district. The lakes on the Alexandria sheet have their beds 
either on Precambric or on Potsdam, and the limestone front is 
more or less remote. They nestle in the extreme upper portions of 
the valley heads on the north side of the divide which runs through 
the region, and has just been described. They are in the extreme 
upper portions of the valleys of north-flowing streams, instead of 
occupying a special position in the valleys of southerly streams, as 
in the case of the Ontarian lakes, and in this lies their chief dif¬ 
ference from those. Hyde lake, in the northern portion of the 
Theresa sheet, conforms more nearly to the Ontarian type, though 
in Potsdam instead of Precambric, and Perch lake seems the shallow 
remnant of another lake of similar type. The Alexandrian lakes, 
however, differ as specified, and herein lies also the reason for their 
localization. The old divide runs into higher ground passing east¬ 
ward, and the relations of the rocks shift. The streams there rise 
in the Precambric and run northward into the Paleozoic rocks of 
the St Lawrence valley, while our lake valleys here commence in 
Potsdam and run north into Precambric. 

Most of the lakes seem to be in rock basins, Crystal, Sixberry 
and Millsite certainly are, and Butterfield probably is. Crystal lake 
is entirely in Potsdam though its bed may be on the Precambric, 
and is walled by high and continuous sandstone cliffs, with the 
sharply cut valley head but a short distance back from the lake 
margin [pi. 34]. Sixberry, Millsite and Butterfield are partly 
walled by Potsdam, with characteristic cliffs, and with valley heads 
cut in Potsdam, but with their beds in Precambric [pi. 54]. The 
beds of the two latter are in large part in Grenville limestone. Six- 


1 Op. cit. p. 217. 



Plate 34 



Head of Crystal lake, 2 j 4 miles south of Redwood, looking north down the lake. Cliff of Potsdam sand¬ 
stone, characteristic basin wall, seen at right. Compare plate 51. H. L. Fairchild, photo, 1908 























Bared surface of Tribes Hill limestone, i mile west of Lafargeville and close to the point from which plate 15 
was taken. The joints run n. 70° e. and the view shows that some solution takes place along them even in this 
rock; in fact the stream is now flowing below ground and breaks out as a large spring at the base of the rock 
wall shown in plate 15. H. P. Cushing, photo, 1908 






















GEOLOGY OF THOUSAND ISLANDS REGION 


133 


berry is surrounded by quartzite and granite and there is no known 
evidence of limestone in the bed. 

Whether these basins were dug out by ice, or have resulted from 
warping, we are unable to say. In either case we can not see why 
no lake was formed in the valley which heads at Browns Corners, 
and is of identical type with the others. The extreme head of 
a valley up which the ice was moving would seem an unlikely place 
for it to dig. Solution of limestone may have aided in the forma¬ 
tion of some of the basins. Though we are unable to account for 
them to our satisfaction, their localization seems to us unquestion¬ 
ably due to the localization of the especial type of valley heads in 
which they occur. 

Underground drainage 

It has previously been shown how, in the more soluble limestones 
of the district, chiefly the Black River and upper Lowville, rain 
water widens the joint cracks by solution, and much of the surface 
water of the district passes down through these fissures to under¬ 
ground flow [pi. 26 and 27]. The Leray limestone is more soluble 
than the Lowville and the chief underground drainage of the 
region is in Leray districts, the underground waters running 
along on the upper surface of the Lowville, slowly enlarging 
their channels by solution. But there are also underground waters 
in the Lowville the upper beds of which are more soluble than those 
beneath. Even in the Theresa formation similar action is at times 
seen. In plate 35 may be seen bared Theresa surfaces in the bed 
of a brook, with joints considerably enlarged by solution, sufficiently 
so to allow the water of the creek to entirely disappear through 
them, to emerge a few yards away at the base of the cliff shown in 
plate 15, the cliff being part of the rock wall of a somewhat filled 
Tertiary valley, that of the Chaumont river. During the spring 
floods the underground channel can not care for the entire flow, and 
part of it remains at the surface, flowing over the rock exposed in 
the view. In the Leray and Watertown limestone districts are many 
stream beds of bare rock, totally dry throughout the summer, with 
their waters underground, but showing plainly the incapacity of the 
underground channel to care for flood waters, which flow in part at 
the surface, and keep the beds thoroughly washed out. Examples of 
such are the creek coming into the Black river from the south at 
Felts Mills (southeast corner of Theresa sheet), and the bed of 
Philomel creek near Brownville. Much underground water comes 
into the Black river, all across the district. 


134 


NEW YORK STATE MUSEUM 


With enlargement of the underground tunnel the roof tends to 
cave in, at first where thinnest, followed by gradual lengthening. In 
most cases the cover is thinnest toward the stream mouth and cav¬ 
ing in begins there and works slowly upstream. In the case of the 
creek at Felts Mills, just referred to, the map shows Lowville lime¬ 
stone in its bed for a half mile above its mouth, beyond which the 
Leray forms the bed rock. In the Lowville for part of its 
course the stream is above ground, and the point where the forma- 
tional contact crosses the stream marks the point of emergence 
from underground, and the slow upstream working of the roof 
cave in. In plate 36 is a rather unsatisfactory view of the caved 
roof of a small stream, unsatisfactory because no position of the 
camera which looked upstream could be obtained, and we are here 
merely looking across from one bank to the other, with the nearer 
bank somewhat hiding the view of the opposite one. The stream is 
a small one, fed by the underground waters of a Leray prom¬ 
ontory of no great extent, but its waters emerge from well down 
in the Lowville, (which alone appears in the plate) and can be 
seen in the extreme lower left-hand corner. The caving extends 
many yards upstream and amounts to some 20 feet in hight at 
the lower end. 

Plate 37 gives an interesting illustration, on a small scale, of 
another feature. The view shows a Lowville platform, surfaced 
by a resistant layer of somewhat less solubility, and, on the right, 
the point of emergence of a small, wet weather stream, flowing in 
a shallow underground channel in the more soluble material un¬ 
derneath. The stream course then curves across the foreground 
and passes backward and toward the left, its course margined by 
the projecting edge of the hard layer, which has otherwise been 
removed from the channel with the exception of the fragment 
left as a tiny “natural bridge ” on the left. 

As already pointed out by Ruedemann, in his account of the Low¬ 
ville inkers in the Leray limestone, very interesting under¬ 
ground features are shown in the Perch river valley about Limerick 
(Clayton sheet). The rock structure there seems to us to be anti¬ 
clinal, with the Leray limestone at Limerick marking the 
site of a sag, and the Lowville inlier, just south, the site of a 
dome of the anticlinal crest. North of Limerick increased south¬ 
erly dip transfers the stream from the Lowville to the Lerav 
horizon, south of it diminished south dip transfers the stream back 
to the Lowville again, the point of transfer being marked by a fall 
[pi. 23] as is the rule in the streams of the region when passing 


Plate 36 



Caved-in roof of a small underground stream in Lowville limestone, 
nearly 3 miles west of Sanford Corners, Theresa quadrangle, looking 
north A good position for the camera could not be obtained so that the 
view does not exhibit the conditions clearly. The issuing stream shows 
in the lower left-hand corner. H. P. Cushing, photo, 1907 


















Plate 37 



A less soluble, overlying a more soluble layer of Lowville limestone. A small cavern in the latter and 
covered by the former shows on the right, and a miniature “ natural bridge ” left in the wearing away 
of both shows on the left; 3 miles northwest of Sanford Corners. H. P. Cushing, photo, 1907 











































Plate 38 



Perch river emerging from beneath a limestone wall after flowing underground for Y\ mile. Note the 
sunken appearance of the limestone of the wall. H. P. Cushing, photo, 1908 




























































































































































GEOLOGY OF THOUSAND ISLANDS REGION . 1 35 

from the Leray to the Lowville. Blit when increased south 
dip brings down the Leray again, at the south end of the 
inlier ? the formation appears as a wall across the valley, and the 
stream follows the Lowville underground, though its course is 
marked by a depression in the surface of the Leray above. 
After flowing underground a short distance the river reappears at 
the surface, or more strictly the surface comes down to the river 
level, owing to caving down and removal of the Leray. In 
plate 38 this emergence of the stream is shown. It quickly passes 
again underground. The process seems definitely the enlargement 
of an underground channel by solution until the roof becomes un¬ 
supported, sags and caves in where thinnest, with succeeding grad¬ 
ual extension of the caving in process, both up and down stream. 
About Limerick the Leray limestone forming the stream walls 
is shown in all stages of disturbance due to this undermining pro¬ 
cess. The view in plate 23 shows the process in an early stage, 
and that in plate 39 in a much more advanced stage, the Leray 
here being in a condition for which Ruedemanirs term of 
“ scrambled ” is so absolutely applicable, that we can not refrain 
from utilizing it. 

In plate 40, a view of the stream above the falls at Limerick, 
we seem to have a direct exposition of what the character of the 
stream is when underground. It seems distinctly a solution, not a 
corrasion, channel following the joints in beautiful, zigzag fashion. 
The chief part of the course shown in the view is on a northwest 
joint, but in the foreground, and also in the background, it is 
along a set of north joints. It seems to us highly probable that 
the stream was formerly underground here. Unquestionably the 
channel is due to solution along, and guided by, the joints. The 
locality is so suggestive that it is a pity a longer portion of the 
stream’s course can not be photographed. A contrasting view, that 
of plate 41, shows a limestone surface (the same limestone) cor- 
raded and etched by surface solution and wear. 

The influence of the low folds in the Paleozoic rocks in causing 
falls in the streams which more or less directly flow down the dip, 
has just been noted in the case of the fall at Limerick. The course 
of the Black river across the south margin of the map furnishes a 
fine illustration of a stream whose fall is precisely that of the dip, 
and along which, owing to variations in the amount of dip, re¬ 
peated falls occur over identically the same rock horizon. The 
river here has cut a shallow valley in rock, in postglacial times, and 
the chief falls in this part of its course are at Felts Mills, Black 


I 36 NEW YORK STATE MUSEUM 

River village, Watertown, Brownville and Dexter; and at each 
locality use is made of the water power. Every one of the falls 
is over the massive Leray limestone into the Lowville beneath, as 
well shown in Ulrich’s excellent panoramic view of the main 
fall at Watertown fpi. 42]. There are minor falls of the same 
type between the chief localities. Below the fall the river flows 
along in the Lowville until the steepened dip on the western limb 
of an anticlinal fold carries the overlying Leray limestone down 
to, and beneath, the water surface, forming the bottom of a shallow, 
synclinal trough [see pi. 28 for such steepened dip at Brown¬ 
ville]. In this the dip flattens, and then becomes low east, bring¬ 
ing the Leray base back to stream level, and giving opportunity 
for development of the fall as the water passes on to 
the less resistant Lowville beneath, the fall so begun slowly 
cutting back up stream with gradual increase in hight. Down 
stream the river remains on the Lowville under the general low 
anticlinal arch, until the drop of its western limb again puts the 
Leray limestone beneath the river level, with repetition of 
the previous conditions and another fall where the limestone comes 
back again. Because of the westerly dip the western limb of the 
anticlines is steeper than the eastern, and the river cuts the bottom 
of each syncline at substantially the same horizon. The diagram 
[fig. 12] will illustrate the conditions, which are somewhat excep¬ 
tional, better than can be done verbally. 





Fig. 12 Diagram illustrating the rock structure which gives rise to the successive falls 
in the Black river, the heavy line representing the river bed with three falls-, and the sinu¬ 
ous dotted line the base of the Leray limestone, showing how, due to the folding 
each fall is over the same rock horizon as its predecessor. Dips and fall of river muc • 
exaggerated ^ 

PLEISTOCENE GEOLOGY 1 
History 

A brief outline of the Pleistocene history and its relation to the 
earlier time is given on pages 23 and 24. 

At least three distinct episodes are recognized in the recent geo¬ 
logic history of our region. These are (1) burial under the ice 
sheet, (2) burial under standing waters, (3) renewal of the ex¬ 
posure to the atmosphere. 

Glaciation. The glacial theory has long since passed into the 
category of accepted fact. That our area has been subjected to 


1 By H. L. Fairchild. 










Plate 39 



Leray limestone overlying Lowville, banks of Perch river at Limerick, near the point at which plate 21 was 
taken. Shows the Leray breaking up and working down the bank, o\\ ing largely to solution of the Lowville be¬ 
neath. H. P. Cushing, photo, 1908 










Plate 40 



Perch river above the falls at Limerick, Clayton quadrangle [see pi. 23]. The 
rock is Leray limestone and the stream course here follows enlarged joint 
cracks, first one set and then another. The enlargement seems wholly owing 
to solution and likely was formerly an underground channel. Looking north¬ 
west and upstream. E. O. Ulrich, photo, 1908 












































































Plate 41 



Stream erosion of Leray limestone, west edge of Watertown; north bank of Black river. Looking 
south. H. L. Fairchild, photo, 1908 



















Plate 42 



Fall in the Black river at Watertown; river falling over the lower bed of the Leray limestone into the Lowville 
beneath. E. O. Ulrich, photo, 1908 




















. 
















' 













- 


































GEOLOGY OF THOUSAND ISLANDS REGION 


137 


the rubbing and grinding action of a continental ice sheet has long 
been recognized, and now it seems almost certain that instead of 
only one there have been several ice invasions of the territory. 
Students of glaciation find evidences of multiple glaciation in the 
Mississippi basin, in Canada, in New England and in Pennsylvania. 
It seems impossible that New York should have escaped occupa¬ 
tion by ice sheets that buried surrounding territory. In the Mis¬ 
sissippi basin the glacial epochs have been named as follows, in 
order of time: Jerseyan, Kansan, Illinoian, Iowan, early Wisconsin 
and later Wisconsin. While there is some doubt as to the validity 
of the Iowan yet the multiplicity of the glacial invasions seems 
to be a fact. The intervals between the glacial stages, the inter¬ 
glacial epochs, are believed to have been long periods of temperate 
climate. It seems possible that our present time of release from 
glacial conditions may be only a warm interval between the latest 
ice invasion and another invasion to come in the near (geologi¬ 
cally) future. 

This matter of multiplicity of ice invasions is here emphasized 
for the reason that the glacial features of our district seem to re¬ 
quire for satisfactory explanation the work of more than a single 
ice sheet. The glacial phenomena will be described in proper order. 

Submergence. Lake Iroquois. As the latest glacier waned 
and the front receded and moved northward the ice was replaced 
by a body of water, the glacial lake Iroquois. This great lake, held 
in the Ontario basin by the ice barrier blocking the St Lawrence 
valley, and with its outlet at Rome to the Mohawk-Hud son, laved 
the receding ice front continuously over all the area described in 
this paper. An important effect of this condition, which the reader 
should hold in mind, is that all the materials left by the waning 
ice were laid down beneath the Iroquois waters, and are conse¬ 
quently more or less modified by the water action. 

The present altitude of the Iroquois beach east of Watertown is 
733 feet. The only point on the entire area covered in this paper 
which is sufficiently elevated to reach the Iroquois plane is the ex¬ 
treme southeast corner of the area, as shown at the bottom of the 
Theresa sheet, [pi. 44]. Here the nose of the Rutland promontory 
brings the 800 foot contour on the map and the Iroquois shore line 
is a steep cliff on the limestone scarp. On account of the postglacial 
uplift and northward tilting of the region the Iroquois plane, and all 
later water planes, rise to the north. On the parallel of Redwood 
it is estimated that the Iroquois water surface was about 800 feet, 
and at Chippewa Bay toward 900 feet. The depth of water over 


I38 NEW YORK STATE MUSEUM 

the plain at Watertown was 200-250 feet, at Lafargeville about 
350 feet, and over the plains at Chippewa Bay about 550 feet. 

Eventually the ice barrier weakened in the St Lawrence valley and 
the Iroquois waters found a new outlet north of the Adiron- 
dacks which was lower (at that time) than the old outlet south 
of the Adironclacks by the Mohawk valley. One point of escape 
was the “ Covey Hill gulf,” precisely on the international bound¬ 
ary between New York and Canada, about 4 miles northeast of 
Clinton Mills. 1 The Covey gulf is a great V-shaped gorge in hard 
Potsdam sandstone, leading north of east, and it carried the waters 
of the second stage of Iroquois, or the Hypoiroquois, over to some 
lower level in the Champlain basin. From aneroid measurements 
it is estimated that the altitude of the head of the gulf is about 
850 feet, or perhaps somewhat higher, but when the gulf was made 
the district was at least 460 feet lower than it is today, and must 
have been lower than the Rome outlet, which is now 430 feet. It 
appears that the Covey gulf outlet was not much lower that the 
Rome outlet, perhaps 50 feet and possibly 100 feet. It might seem 
as if the Covey gulf outlet represented sufficient length of time 
for the lake waters at that level to produce recognizable features 
along favorable stretches of the shore line, and such may yet be 
found. Dr Gilbert has suggested that possibly the Covey gulf was 
chiefly cut by a more ancient glacial outflow and that the Hypo¬ 
iroquois may have done little work beyond clearing out the old gorge. 

As the ice front melted back this second stage of the glacial 
waters of the Ontario basin found yet lower escape along the north 
side of Covey hill, between the ice wall and the rock slope. This 
third phase of the Iroquois waters must have been short-lived, with 
rapidly falling levels, the river flow only terracing the sandstone 
slope. It is thought that the final effect of this down-draining of 
the glacial waters was to bring them into confluence with the oceanic 
waters which then occupied the Champlain basin and are called 
the Champlain (Woodworth's Hochelagan) sea. The supposed ex¬ 
tension of the sea-level waters into the Ontario basin is known as 
Gilbert gulf. 2 

Gilbert gulf. If our present conception of the history is 
correct the sea-level waters covered nearly all the territory 
comprised in our five quadrangles. On the north slope of 
Covey hill the Champlain beaches have an altitude of a.t least 
460 feet, which is the measure of the amount of land uplift in 

1 For description and illustrations of this outlet see paper by J. B. Wood- 
worth, Ancient Water Levels. N. Y. State Mus. Bui. 84. Ebenezer Emmons 
and G. K. Gilbert had noted the feature. 

2 Gilbert Gulf (Marine Waters in Ontario Basin). Fairchild, H. L. Geol 
Soc. Am. Bui. 17:712-18. 



GEOLOGY OF THOUSAND ISLANDS REGION 


139 


that district since the ice left that locality. The Gilbert plane 
declines to the south and southwest and on the south border of 
our area the beaches are 390 feet [pi. 45]. North of Lafargeville 
[pi. 46] strong beaches lie at 440 feet, and 2 miles southeast of 
Redwood a bar is found at 450 feet altitude [pi. 47]. 

It has not seemed practicable to make maps for this writing 
to show all the Gilbert shore lines of the area, but the strongest 
shore features are indicated on the maps, plates 45—47. These 
are wave-built bars and spits and wave-washed limestones. Some 
of these features are shown in the halftones, plates 48-53. Xhe 
southeast portion of our area, being the southeast diagonal half 
of the Theresa sheet, was mostly above the Gilbert waters. The 
submerged parts are such as lie below 400 feet at the south edge 
of the sheet and below 440 feet at the north edge. It will be 
seen that this is the low ground north and northeast of Brown- 
ville, the valley of Perch river, the low ground about Theresa 
and the valley of Indian river. All the rest of the region was 
under the full Gilbert level except the three limestone hills north¬ 
west of Dexter; the limestone plateau between Stone Mills, De- 
pauville and Lafargeville; the limestone plateaus north of Depau- 
ville; the boulder-kame hill 2 miles north of St Lawrence cor¬ 
ners, known as the “Hogback”; and the group of boulder- 
moraine hills north of Lafargeville; one being cut by the edge 
of the Theresa sheet. These areas which received wave action 
so as to leave beach records are mostly shown in the plates 
45, 46 and 48. 

While all surfaces between the highest Iroquois and the Gil¬ 
bert planes have been wave-swept by the subsiding waters, and 
many patches of bared rocks are found at various levels, no 
beach phenomena have been noted between the two planes. All 
the high level shoreline features in our district are confidently 
referred to the sea-level waters. 1 

1 Since this paper has been in type Prof. George H. Chadwick discovered _ 
heavy beaches and deltas of Lake Iroquois in St Lawrence county, and also 
extensive deltas inferior to the Iroquois plane and of uncertain relationship. 
In August 1910 we examined these features and carried the study north¬ 
eastward into Canada. 

The Iroquois plane is now definitely known at several points, the farthest 
east being at Chateaugay with altitude 975 feet. On the international 
boundary at Covey hill the full-hight plane is not much above 1000 feet. 
The head of Covey gulf, the outlet of the lower or Second Iroquois, is 
about 980 feet. 

A recent survey on the Canadian side of the boundary gives us precise 
altitudes for the sea-level beaches (Gilbert gulf), which have at Covey Hill 
post office a hight of a least 523 feet. 

These altitudes are entirely consistent with the figures and facts relating 
to the Iroquois and Gilbert gulf water planes given in this report. 



140 


NEW YORK STATE MUSEUM 


From the Iroquois to the Gilbert levels the waters fell with 
comparative rapidity by the removal of the ice dam. The apparent 
lowering of the Gilbert waters was on the contrary by the very 
slow uplifting of the land out of the sea-level waters. This rising 
of the land must have been so slow as to give opportunity to the 
waves at all minor levels to produce shore line phenomena, and 
many such are found. However, such proofs of the presence of 
standing waters are missing over long stretches of even the summit 
plane, which emphasizes the well recognized fact that absence of 
clear wave work does not necessarily prove the absence of standing 
waters. 

But while beach phenomena may be lacking or weak over wide 
stretches we find other evidences of the waters. Either by the 
lowering of the Iroquois waters over the higher ground or by the 
lifting of the lower ground through the Gilbert waters all the 
land surfaces have been brought into the zone of wave action and 
subjected to erosion or deposition by the agitated waters. In 
consequence the steep slopes, the projecting rock masses, tables 
and knobs, have been more or less cleared of their drift and 
specially of the finer material, which has been shifted to lower 
levels. The broader plateaus and plains have been smoothed 
and the lower grounds, valleys, basins and hollows, have been 
more or less filled or silted with the detritus, sand or clay, washed 
from the higher ground. This action explains two striking- 
characters of the region, the areas of bare rocks and the silt- 
filled basins, which will be discussed later. 

Conclusive proof that the lower waters were confluent with 
the sea would be the finding of marine fossils. Such have not 
yet been found in the Ontario basin, though they are abundant 
in the Champlain and St Lawrence valleys, and marine shells 
have been found as far west as Ogdensburg. 

Atmospheric erosion. The whole region, above the Ontario 
level, has long been subjected to a renewal of the atmospheric 
agencies. The length of time is unknown, but is not equal for all 
the area. For the lower plains, near the present lake, the time must 
somewhat exceed the life of Ontario; while for the higher ground, 
above the Gilbert levels, the time must cover not only the life of 
Ontario but also that of Gilbert gulf. If we estimate the life of 
each of these water bodies as 10,000 years it may give some fair 
conception of the duration in years. For lands above the reach 
of Lake Iroquois its length of life must be added to the time of 
exposure, at least another 10,000 years. It is likely that these fig¬ 
ures are too small rather than too large. 


GEOLOGY OF THOUSAND ISLANDS REGION 


141 


Physiography 

Glacial diversion of the Black river. The history of the Black 
river is not only the most interesting problem connected with the 
evolution of the physiography of the region but specially important 
as it may supply the key to Tertiary drainage of the entire area. 

In only the middle portion of its course has the present Black 
river any pronounced valley. The headwaters and upper section, 
about 30 miles long, lie on the crystallines of the southwest slope 
of the Adirondacks, with no conspicuous valley. The lower section, 
below Carthage, has only a shallow postglacial channel. The great 
valley begins at about Forestport and extends northwest to Car¬ 
thage, a distance of more than 40 miles, and steadily deepens and 
widens northward. At Glenfield or Lowville, near the middle part 
of the valley, the altitude of the river is 740 feet, while the great 
ridge on the west, separating this valley from the Ontario, rises to 
2000 feet, and the breadth of the valley is at least 10 miles on 
the 1300 foot contour. 

Former writers have regarded the Black river as the trunk stream 
of the early drainage which headed the Ontario valley. 1 It appears 
to the writer that that view is a mistake and that quite the oppo¬ 
site is the fact, that the Black river was the headwater of the St 
Lawrence drainage, at least for New York State. 

Plate 43 shows the present hydrography of the region and the 
divide between northward and southward streams of the Ontario- 
St Lawrence valley. Plates 44 and 47 show portions of the divide 
on the larger scale of the topographic sheets. On plate 43 the 
heavy, broken line south of the Black river marks what was the pre- 
glacial divide between Ontario and St Lawrence drainage before 
the Black river was forced by the interference of the ice sheet across 
the divide. The light, continuous line indicates the present and 
shifted divide. It is apparent that below Great Bend the river has 
peculiar and anomalous relationship, and that the divide leading 
east up the Adirondacks slope is newly established. 

In discussion of this problem the theoretic evolution of the drain¬ 
age will be considered first and then the recent history and the 
present features. 

The Black valley was initiated and developed, at least as early 
as the Tertiary uplift, along the contact or overlap of the Ordovicic 
sedimentaries on the ancient crystallines. The west wall of the 

1 Specially the paper by A. W. G. Wilson, Trent River System and the 
St Lawrence Outlet. Geol. Soc. Am. Bui. 15:211-42. Pages 236-38 refer 
to our district. With the entire article excepting the point of the Black 
river relationship we are in hearty accord. 



142 


NEW YORK STATE MUSEUM 


great valley shows all the strata from the Pamelia to the Oswego 
sandstone. The east wall of Precambric rocks is deeply buried un¬ 
der sand plains or delta deposits accumulated in glacial waters. 1 The 
axis of the deepening and north leading valley migrated westward, 
down the slope of the basal crystallines and against the outcrop of 
the sediments. 

The great ridge dividing the Black and Ontario valleys now 
terminates abruptly in the Rutland promontory with a limestone 
scarp about 400 feet high. The point of this promontory is shown 
on the lower edge of plate 44, south of Felts Mills and Black River 
villages. A glance at the Watertown sheet will show how the river 
below Felts Mills clings to the foot of the scarp. A moment’s 
thought will make it evident that these thick limestones did not 
originally end here, but must have extended far north, overlying the 
district toward the St Lawrence. It seems perfectly evident that 
the stratigraphic relations and the erosional conditions which pro¬ 
duced the Black valley above Carthage must once have extended 
much farther northward, and the Tertiary river probably had its 
course northward along what is now the east slope of the St Law¬ 
rence valley, in continuation of the Forestport-Carthage valley. The 
problem is therefore narrowed to the question of the time of the 
removal of the Trenton limestones north of the Rutland promon¬ 
tory, and the date of the diversion of the river from its northward 
into its westward course. 

A singular physiographic feature of the region is the northward 
or rather northeastward direction of all the heavy streams north 
of the Black river. These all flow along parallel with the St 
Lawrence, and in some sections at even lower levels. In normal 
stream development the tributaries should flow toward the trunk 
stream. The Indian, Oswegatchie, Grass, Raquette and St Regis 
are more or less independent of the St Lawrence and are not normal 
tributaries. Their courses have probably been modified, straight¬ 
ened and their parallelism emphasized by repeated glaciation, but 
the latest ice erosion has certainly been insufficient to produce such 
channels. Their direction is in precise opposition to the glacial 
effect and also in opposition to the postglacial uplift of the region. 
It is in harmony with and in continuation of the Black valley, 
curving eastward around the uplifted mass of the Adirondacks. It 
seems altogether likely that these stream courses were developed 
by north leading drainage having practically the same stratigraphic 

1 See a paper by the writer, Glacial Waters of the Black and Mohawk 
Valleys. N. Y. State Mus. Bui. In press. 



EDUCATION DEPARTMENT 
JOHN M CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 

STATE M USETM 



BULLETIN 145 PLATE 44 


Smooth 

till 


/Stony 


ti J-t r< r> 


- 0.-0 0 

o, Q& ? 


500 


Part of Theresa shee - 


M. L. Fairchild 


PLEISTOCENE FEATURES: BLACK RIVER DISTRICT 


LEGEND 


Marginal Drift, 
Moraine 



Ordinary moraine 


V - 'i 


Very stony 


r - --- n 

I > - 4‘f. A 

Boulder lidges 


Marginal Drift, 
Kame 


I_ ■- 

Sand areas 



Sand knolls 


Lake Iroquois 
Features 

\ 

Cliff shoreline 


Delta sandplain 



Bared rook 


Gilbert Gulf 
Features 


Glacial Striae 



Numerals indicate degree 
from meridian 

Drainage Divide 



Between northeast aud 
southwest How. 


























































' 
































































GEOLOGY OF THOUSAND ISLANDS REGION 


143 


relation as that which initiated the Black valley. The only features 
which are not in harmony with the above theory are the southward 
course of a section of the Indian river, above Evans Mills, and of 
the Oswegatchie above Oxbow. Those are probably due to glacial di¬ 
version, similar to that of the Black below Great Bend, but for 
better knowledge we must await the topographic sheets. 

Professor Cushing suggests that north from Felts Mills the pre¬ 
glacial divide might have swung west from the present course, pass¬ 
ing south of Perch lake, through Depauville and south of St Law¬ 
rence corners. The wider valley of the Chaumont north of Depau¬ 
ville and the northward course of French creek favor this view. 
It is cpiite possible that Prewisconsin glacial erosion has caused a 
northward migration of the portion of the divide that was trans¬ 
verse to the ice flow, but the latest ice work seems to have been 
too weak. We may not appeal to forced stream flow during the 
last ice recession, as the region was then burie l under Iroquois 
waters. The northward uptilting of the area tends of course to 
divert sluggish drainage into southward flow, but alone this could 
not be a very effective factor. 

Passing now to certain specific data and features connected with 
very recent history, the reader should note again the intimate rela¬ 
tion and parallelism of Black river to its northward flowing neigh¬ 
bors [pi. 43], after which a glance at plate 44 will show the cause 
of the separation and the character of the barrier. At Great Bend 
and Felts Mills the river has cut into the south side of its own 
delta, that was built in Lake Iroquois. Along much of that stretch 
rock is seen in the bed of the river, beneath the steep wall of the 
delta deposits. North of the delta the ground is 100 feet or more 
lower than the river, and all draining northward. At Felts Mills 
the river has an altitude of 580 feet, while only 1 y 2 miles north, 
and simply across the delta divide, is Pleasant creek, a tributary 
of Indian river, at only 520 feet altitude. The fall from Black 
river to Indian river by Pleasant creek is 200 feet in about 6 miles. 
Further up stream, at Great Bend the river has a large meander in 
the delta and the facility for northward flow may be even better 
than at Felts Mills, but the topographic survey has not covered the 
district. 

The suggestion is natural that possibly a rock barrier is buried 
under the delta, which would be an effective barrier to north escape 
of the river if the delta were removed. Fortunately we have 
specific data. Mr F. A. Hinds, the well known hydraulic engineer 
of Watertown, has pointed out the important fact that the drainage 


144 


NEW YORK STATE MUSEUM 


of the great sponge of sand plain, on which is located the military 
camp, is not into the Black river but north into the Indian river. 1 
Along the north side of the sand plain huge springs gush out along 
the contact with the impervious drift, while such are entirely want¬ 
ing on the Black river side. It is certain, therefore, that if the 
delta at Felts Mills and Black River were not there the river would 
plunge northward. It is equally certain that before the ice invasion, 
and the deposition of the delta and moraine barrier, the river did 
flow northward. The only condition which could produce south¬ 
ward flow would be a northward uplift 20 or 30 feet per mile 
greater than we have today, which is extremely unlikely for this 
district. As long as any of the St Lawrence valley drainage passed 
north the Black river went with it. 

The westward course of the Black river from Great Bend is due 
to glacial diversion. The river is on rock and with no proper valley. 
It is in a postglacial channel. Moreover, there is no south leading 
valley in the Watertown district sufficient for a large river. If 
there were the Black would be in it today as there is no heavy drift 
barrier to block drainage in the district south of Watertown. 

The later history is quite clear. During not only the advance and 
retreat of the latest ice sheet but probably that of earlier ice sheets 
the Black valley high-level waters were forced westward and south¬ 
ward around the Rutland promontory. High on the slopes at Copen- 

1 Extracted from report of Frank A. Hinds to the Water Board of the 
City of Watertown, June 29, 1908. 

the entire country slopes toward the north and west and away 
from the bank of the river which is the highest part. 

The Pine Plains is a sheet of very clean sand from 50 to 75 feet thick 
and covering an area of from 25 to 40 square miles. The sand is so porous 
that all the rainfall sinks directly into it and forms a natural reservoir at 
the bottom. This ground water has a slow movement in the direction of the 
slope but does not become exhausted during the dry season as the constant 
character of the springs at its edge proves. 

While the water of the river opposite the (U. S. military) camp is 100 
feet below the surface of the plains, there is an impervious bed of clay 
and rock underlying the sand which is from 30 to 30 feet above the river. 
This clay may be seen in many places along the bank, though in others the 
sand has run down and covered it over. Five miles to the west the sand 
plateau stops and the clay substratum continues as the surface soil of the 
country; but here it is 100 feet lower than where it commences at the 
river brink under the camp. 

This northwesterly slope of the subsoil determines the direction or flow 
of the underground water and accounts for the fact that there are but few 
and comparatively small springs flowing into the Black river from under 
the plains, while those along the western border of the sand are more 
copious and gather into several creeks or brooks of noticeable magnitude 
which flow westerly into the Indian river. The few springs along the 
Black river bank are where the underground water spills over the easterlv 
upper edge of the clay stratum, but they are comparatively few and small 
. . . . the water which emanates from under the Pine Plains does not 

get into the Black river to any extent worthy of attention. 




UNIVERSITY OP THE STATE OP NEW YORK 

STATE MUSEUM 


EDUCATION DEPARTMENT 
JOHN M CLARKE 
STATE GEOLOGIST 


BULLETIN 145 PLATE 45 


,imei 


H. L. Fairchild, 1909, 


PLEISTOCENE FEATURES: CM AIJMONT- HUOW XVIEUE DISTRICT 


Parts of Clayton and Theresa sheets 


legend 

Gilbert Gulf 
Features 



Bars and spits 


Cliff 


Hypothetic shoreline 



Sandplain; delta (?) 



Bared rock 


Glacial Striae 



Numerals indicate degrees 
from meridian 























































































144 


of the 
camp, 
Along 
the co: 
ing or 
delta ; 
plunge 
and th 
flow r 
ward 
greate 
distric 
north 
The 
to glac 
It is ii 
valley 
there ’ 
barriei 
The 
retrea 
the B 1 
ward r c 

1 Ext 
City oi 

from tl 

The 
and cc 
that al 
the hot 
slope b 
charact 

Whil 
feet be 
and ro 
This cl 
sand h 
plateau 
county 
river b 

This 
of the 
and cc 
the pk 
copious 
which 
Black 
upper i 

get int 






GEOLOGY OF THOUSAND ISLANDS REGION 


*45 


hagen and Champion are the glacial channels [see footnote 
p. 142]. The Rutland Hollow is a capacious valley cut ob¬ 
liquely across the nose of the promontory, parallel in direction with 
both higher and lower glacial channels of Black valley outflow, and 
was undoubtedly given its form and dimensions by glacial drainage. 
When the Black valley waters were lowered into Lake Iroquois the 
Black river built its delta in the lake northwest of Carthage, partly 
banked against heavy moraine. When Lake Iroquois was lowered 
into Gilbert gulf the Black river found its ancient course obstructed 
by the delta and moraine deposits and was compelled to follow 
around the rock promontory in the path of the stronger shore cur¬ 
rents in the lake. West of Watertown the river dropped its detritus 
in the sea-level waters (Gilbert gulf), and when these waters were 
lowered by the land uplift the river pursued its chance course over 
the rock toward the retreating water body. 

To epitomize: It seems certain that the earliest drainage which 
we can locate must have been along the weak zone of the overlap 
of the sedimentary rocks on the Precambric, in north and north¬ 
east continuation of the Black valley. Preceding the latest ice in¬ 
vasion the Black river probably flowed north. Just what may have 
occurred during the Tertiary uplift and the earlier Pleistocene we 
do not know. It is possible that there are unsuspected elements 
in that long history, but there is no discovered reason for any 
preglacial southward drainage across the divide as mapped in plate 
43. The really uncertain factor is the glaciation earlier than the 
Wisconsin epoch. The writer is inclined to credit to glaciation 
earlier than the Wisconsin considerable influence in producing the 
parallelism of the rock forms and the drainage lines along the St 
Lawrence depression ; and the bluntness and roundness .of the Rut¬ 
land promontory; and the cutting of the Rutland Hollow. 

Topographic features. Parallelism. The topographic ele¬ 
ments of the area have a conspicuous parallelism, about northeast 
and southwest, in accordance with the St Lawrence valley and river. 
On the Clayton and Theresa sheets this shows clearly in the stream 
and valley courses and in the trend of the plateaus and rock hills. 
On the Alexandria and Grindstone sheets the parallelism appears 
in the elongation of the rock knobs and the form of the lakes and 
the islands in the river. This character prevails down the valley 
far beyond our district, as shown by the river courses which instead 
of flowing directly to the St Lawrence follow along in parallel 
courses [pi. 43]. 


146 


NEW YORK STATE MUSEUM 


The genesis of this prevailing orientation probably involves factors 
which cover the entire geologic history of the region. In an earlier 
chapter Professor Cushing has shown that during the time of the 
earliest sedimentation in the region there was alternately a tipping 
to the northeast and the southwest, the fulcrum of motion lying 
across our district, initiating what is called the Frontenac axis 
[p. 95]. The broad depression of the valley is thought to be partly 
the result of sagging, accompanied by jointing, one main trend of 
joints having fair agreement with the trend of the valley. 
Cushing also shows that some slight folding occurred in Paleozoic 
time and stronger folding in Precambric time which probably had 
some directive influence on the drainage [p. 108-115]. 

The larger existing features and general stream directions were 
developed during Tertiary time under subatmospheric erosion. Dur¬ 
ing Pleistocene time the St Lawrence valley, being closely in line 
with the spreading flow of the ice sheet over the region, served as a 
trough for the advancing and the waning ice lobes. We do not know 
the number of ice invasions but it seems quite certain that the latest, 
or Wisconsin, ice sheet was preceded by others of probably greatei 
effectiveness in erosion. The striking parallelism of the minor 
features of the topography is probably due in some degree to re¬ 
peated glaciation, the alternation of ice flow of the glacial epochs 
and the stream erosion of the interglacial epochs mutually assisting 
or guiding each other. 

Dominant types. The topographic features in the sedimentary 
rocks are naturally an expression largely of the stratigraphic char¬ 
acters. This has already been discussed in a former chapter by 
Cushing [p. 121-136]. In the present connection we have to con¬ 
sider the topography in its relation to the glacial and glacio- 
aqueous history. 

Leaving out of account for the present the localized and scanty 
moraine deposits, we may distinguish two dominant types of the 
surface relief in the area, (1) the rounded rock hills or knobs of 
rather striking relief in the northern part of the area, in the district 
of Potsdam and Precambric rocks, and (2) the broad level stretches 
which characterize the southern half of the area, where the rocks 
are well stratified. 

Rock knobs. In the northern part of the area, covered by the 
Grindstone and Alexandria sheets and the northeast part of the 
Theresa sheet, the crystalline rocks and the lower Potsdam appear 
commonly in the form of knobs or bosses, singly or in clusters and 
chains, as illustrated in plates 6 and 7. Cushing lias shown [p. 54] 






EDUCATION DEPARTMENT 
JOHN M. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 

STATE MUSEUM 


BULLETIN 145 PLATE 46 


H. L. Fairchild, 1909 . 


PLEISTOCENE FEAT! RES: CLAYTON-LAFARGEVILLF 


Parts of Clayton and Theresa sheets 


1x7 

1 

1 V 


/ \ 

r ;«T 



\ 



v v3»5« 

y 


LEGEND 

Marginal Drift, 
Moraine 


Ordinary moraine 


Very stony 


-Y-- 

J 9 O. <3 0 

,0 p a. 


Boulder ridges 


Marginal Drift, 
Kame 


Sand areas 


o o o o 
1 n O o c 
0600 


Boulder kames 


Glacial Stream 
W ork 

kz _ 1 

Eskers 


Gilbert Gulf 
Features 



Bars and spits 


Cliffs 


V _ 

Hypothetic shoreline 



Bared rock 


Glacial Striae 



Numerals indicate degrees 
from meridian 


















































































































I 4 < 


wh 

chj 

eai 

to 

acr 

[P- 

the 

joi 

Cu 

tin 

sor 

r 

deA 
ing 
wil 
tro 
the 
or 
eff< 
fea 
pea 
anc 
or , 
1 

roc 

act' 

Cu 

sid* 

acjt 

I 

mo 

sui 

rati 

of 

wh 

"are 

I 

Gri 

Th< 

con 

cha 






GEOLOGY OF THOUSAND ISLANDS REGION 


H7 


that the knobby surface of the crystallines is the immensely ancient 
erosion surface of the Precambric land area, which had been buried 
under Potsdam sediments and only recently uncovered. Ice erosion 
seems to have had very little influence in shaping the surface, merely 
rounding and smoothing the knobs. 

the major axes of the knobs are roughly parallel with the valley 
and the ice movement, but the relation to the latter is mostly casual 
and not genetic. The struck or northwest side commonly shows 
more erosion, but frequently the difference is not evident. As a 
rule the crystallines have not retained their striae and polish as well 
as the Potsdam sandstones. 

Plains of erosion. I he broad plains, either rock or rock floored, 
are regarded as the product of long eras of atmospheric erosion 
with later glacial planing and a finishing touch of wave smoothing. 
They are found in districts where the sedimentary rocks are persist¬ 
ent in considerable thickness so as t6 cover the Precambric and the 
lower and irregular Potsdam. Broad tracts of this class consisting 
of upper Potsdam occur south of Chippewa Bay and toward Alex¬ 
andria Bay. Theresa dolomite forms the plain north of Chippewa 
Bay and covers large areas on the parallel of Plessis and Clayton. 
South of the parallel of Lafargeville the plains and plateaus are 
limestones. 

7 

The earlier ice sheets seem to have lifted or plucked away the 
weathered and weak superficial layers of these stratified rocks down 
to some firm, less jointed and more resistant bed; but the flatness 
and smoothness of these level stretches is partly due to the latest 
action, the leveling action of the shallowing waters. The glacial 
drift is commonly thin on these plains and patches of bare rock are 
very frequent, sometimes acres in extent, specially on the Potsdam. 
A good example is seen at Plessis, which village was formerly called 
“ Flat Rock." On the highways rock frequently occurs in unex¬ 
pected manner and often forms the wagon track for considerable 
distance. Although glacial polish and striae occur frequently on the 
Potsdam the majority of exposures have either lost their smooth¬ 
ness or were never severely rubbed. On the other strata glaciated 
surfaces are not common. 

These plains have been trenched by stream erosion and many of 
the valley walls are yet steep, those of Chaumont river for example. 
The differential erosion of the several strata has produced scarps 
or benches about the margins of the higher plains which are fre¬ 
quently striking features of the landscapes and sometimes are per¬ 
sistent for long distances. These have been described in a former 


148 


NEW YORK STATE MUSEUM 


chapter in connection with the stratigraphy [p. 129]. The valley 
and scarp topography is certainly older, at least in great part, than 
the latest glaciation. 

Plains of deposition. Flat stretches of detrital deposits occupy 
the valleys and basins in the northern part of our area and the low¬ 
lands in the southern part. They are broadly developed over the 
southwestern part of the area, covering nearly all of the Cape Vin¬ 
cent sheet and a large part of the inferior levels of the Clayton sheet. 
Doubtless the more elevated of these detrital plains have rock floors, 
those about Lafargeville and Clayton for instance, but the rock is 
masked; while the valley and basin fillings are deep clay. 

These plains are chiefly clay, though sometimes sandy silt and 
occasionally sand. They represent the distributing and leveling 
work of standing waters, Lake Iroquois and Gilbert gulf, and are de¬ 
scribed with reference to origin in a later chapter, page 156. The 
best example of the sand plains may be seen 3 miles southwest of 
Theresa, crossed by the Clayton branch of the New York Central 
Railroad between Theresa Junction and Strough. Beyond this, both 
east and west of Lafargeville, the plains are clay. From the trains 
on the Cape Vincent branch of the railroad the clay plains may be 
seen spread far and wide, as flat as a prairie, all the way from 
Limerick to Cape Vincent, with a few interruptions of rock or of 
till ridges. 

The more extensive, upland clay plains shade ofif into till, while 
some of the valley clays are conspicuously pitted, as if deposited 
over ice [p. 158, pi. 47]. 

Lake basins. Perhaps the most puzzling of the physiographic 
features are the basins or basinlike valleys with steep rock walls. 
These are more striking in the district of Potsdam and Precambric 
rocks of the Alexandria quadrangle, where they hold an interesting 
group of lakes, the only lakes in our area, excepting Hyde and 
Perch lakes on the Theresa quadrangle. The five lakes of our 
area, near Redwood, shown in plate 47, are only the western mem¬ 
bers of a large group. Some basins without lakes and some steep- 
walled valleys in limestones on the Theresa and Clayton sheets are 
probably of similar genesis. 

Two facts in connection with these basins are specially to be 
noted, the steep, scarplike rock walls and the very small amount 
of glacial drift. These features seem abnormal in a district that 
has been subjected to probably repeated glaciation. While these de¬ 
pressions are mostly oriented in general harmony with the physio¬ 
graphic alinement of the region, having a northeast-southwest atti- 



EDUCATION DEPARTMENT 
JOHN M. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 

STATE MUSEUM 

jf-^ 


BULLETIN 145 PLATE 47 


.'Cs'liniVste*1 >/„.]<■ 
Maple. /. 


NDJ 


Part of Alexandria Bay sheet 


PLEISTOCENE FEATURES 


H. L. Fairchild 


4LEXANDRIA BAY- R ED W( K >I> DISTRICT 


LEGEND 


Marginal Drift, 
Moraine 


Ordinary moraine 



Very stony 


Marginal Drift, 
Kame 


Sand areas 


’! 11 

Sand knolls 


Boulder kaines 


Glacial Stream 
Work 

Eskers 


Gilbert Gulf 
Features 



Bars and spits 


Clay Plains 


Fitted clay 


Glacial Striae 



Numerals indicate degrees 
from meridian 

Drainage Divide 



Between northeast and 
southwest flow. 



























































































148 

chapter 
and sea 
the late 
Plain. 
the vail 
lands ii 
southw 
cent she 
Doubtle 
those a 
masked 
Thes< 
occasio 
work of 
scribed 
best ex 
Theres; 
Railroa 
east an 
on the 
seen s] 
Limeri 
till rid: 

The 
some c 
over ic 
Lake 
feature 
These 
rocks c 
group 
Perch 
area, r 
bers o 
walled 
probab 
Twc 
noted, 
of gla 
has be 1 
pressic 
graphi 




GEOLOGY OF THOUSAND ISLANDS REGION 


149 


tude ? which very likely was partly controlled by early glaciation, 
yet a significant number are transverse. Some basins in the vicinity 
of Alexandria Bay [pi. 47] and others south of Clayton [pi. 46] 
do not conform to the prevailing direction, and the basins of tlie 
Redwood lakes are so irregular in form as to rule out ice erosion 
as the dominant agent. It seems certain that these basins, like the 
scarp borders of the plateaus, are due to atmospheric agencies 
with only small and indeterminate glacial effects; or that they cer¬ 
tainly antedate the latest ice invasion. One would naturally sup¬ 
pose that the scraping ice sheet would have rubbed the transverse 
valleys full of drift. In some valleys and against some scarps the 
amount of drift is sufficient to be noticeable, but it only masks the 
foot of the cliffs. In many relatively deep depressions the drift 
is scarcely perceptible, though some may be buried under the lake 
silts which occupy the valley bottoms. 

Besides the lack of drift filling is to be noted the absence of pre¬ 
glacial talus accumulations. In places the Potsdam is so freely 
jointed that the cliffs break down under the frost quite rapidly and 
heavy block taluses occur which are evidently postglacial; but in 
most cases there is little or no talus, specially outside the Potsdam 
rocks. In the case of the limestone walls solution might be suffi¬ 
cient agency to remove the products of weathering, and this might 
also apply to the Precambric Grenville limestones which form some 
part of the basins of the Redwood lakes; but such removal can 
not apply to the almost imperishable Potsdam sandstone. The 
older fragmental deposits produced by the recession of the cliffs 
have been removed, most likely by the glacial ice, but without 
leaving much drift in their place. 

The lack of drift in the basins and over the plains clearly implies 
a lack of drift burden in the latest ice sheet. The cause of this 
will be discussed later [page 172]. The small abrading power of 
the ice was probably due to its lack of tools, and evidently it did 
not have sufficient power of “ plucking ” or removing blocks in 
mass to destroy or even seriously cut the steep ledges and scarps 
which stood across its path. 

One suggestion in partial explanation of the somewhat contradic¬ 
tory features, is that stagnant ice occupied the strong depressions 
over which the upper ice moved by shearing. This would fairly 
account for the absence of heavy drift in the basins and valleys 
and the protection of the walls. Another suggestion takes account 
of the fact that when the latest ice sheet disappeared from this 


NEW YORK STATE MUSEUM 


150 

area the front was faced by about 400 feet of water in the Red¬ 
wood district. Just what that condition implies in its effects on 
the ice and the drift is uncertain. We do not know whether the ice 
melted back as a steep, high front under the dissolving influence 
of the water, or whether it melted as a thinning sheet, partially pro¬ 
tected by its scanty drift, until it was lifted by the water and rafted 
away. 

To epitomize: We conclude that the basins and stronger valleys 
were excavated by weathering and stream erosion in preglacial or 
interglacial time, with perhaps some help from early ice erosion; 
and that the latest ice sheet had little effect beyond clearing out 
the debris which it found. 

Glacial deposits 

Introduction. General features. Compared with areas to the 
southward the area under description has very scanty drift, and 
has suffered little recent ice erosion. The area did not lie in the 
zone either of dominant deposition or dominant erosion of the 
latest ice sheet. Over large portions of the area the rocks are 
nearly bare, and even in the districts where the drift cover pre¬ 
vails the rock appears frequently and unexpectedly. The amount 
or depth of drift increases southward but the only heavy moraine 
lies in the southeast corner of the area [pi. 44]. 

In considering the character and distribution of the drift it is 
necessary to emphasize again the fact that during the ice recession 
the whole area was submerged in the waters of Lake Iroquois, and 
this was followed by the sea-level waters of Gilbert gulf. The 
marginal drift was all deposited under subaqueous conditions, and 
wholly subjected to the distributive action of the shallowing waters. 

Over the northern part of the area, where the rock foundation 
is either Potsdam or Precambric and the land surface irregular, the 
scanty drift is largely in the depressions, due specially to the work 
of the shallow waters. Over the southern districts, where the lime¬ 
stones form wide plains or plateaus, the drift is usually a veneer 
giving the broad stretches flat or gently rolling surfaces. Because 
• of the lack of drift the preglacial valleys are still open, and one of 
the characters of the region is the valleys and basins with steep 
rock wall's and silt-plain bottoms. The valleys of French creek 
and Chaumont river are open down to Ontario level; and the Perch 
lake valley is filled to only 70 feet over Ontario. The open char¬ 
acter of these southern valleys is to be only partly explained bv the 







GEOLOGY OF THOUSAND ISLANDS REGION 1 5 1 

stream erosion of the clays which constitute the bulk of the drift. 

1 he existence of the Redwood lakes in the northern district is an 
evidence of lack of drift filling. 

The normal and common form of drift in regions of glaciation, 
the stony clay or clayey mixture of rock rubbish known as “ till,” 
is widely found but in relatively small amount. The larger drift 
masses are of three kinds: sandy or “kame” areas; boulder mo¬ 
raines; and pitted clay plains. The extensive plains of water-laid 
clay are regarded as glacio-aqueous deposits, and are described in 
a later chapter. 

Till. In the northern portion of the area, where the rocks are 
Potsdam and crystallines and arenaceous materials prevail, the 
scanty till is sandy and stony. In the southern district where the 
strata are wholly limestone these give a clayey texture to the drift 
sheet. 

The superficial till is usually incoherent and yellow or yellowish 
gray in color. In a few places a compact, hard, blue or blue gray 
till may be found which is regarded as the product of ice action 
earlier than the Wisconsin. The most massive exposures of the blue 
till are found south of our area, at Watertown [p. 166]. 

No drift masses that could be definitely recognized as drumlin 
have been noted in our territory, though they, do occur over the 
line on the south, north and south of Watertown. Some molding 
of the till surfaces suggest drumlinizing of the drift, but appar¬ 
ently the till was too scanty to be rubbed into definite drumlin 
masses. 

Moraines. One heavy moraine lies in the southeast corner of 
our area, between Black River and Evans Mills, mapped in plate 
41. This is the only mass of drift of notable size in the limestone 
district. In the northern part of the area, where the Potsdam sand¬ 
stone and the knobby crystallines give irregular surface and rather 
sharp relief, patches of rough and stony drift that may be re¬ 
garded as morainal are quite frequent; but the only grouping 
which merits the name of moraine belt lies about Clayton and east¬ 
ward north of Lafargeville, shown in plate 46. In general it may 
be said that the peripheral or morainal drift is not collected in well 
marked lines but is scattering, patchy and indefinite. In districts 
where the Potsdam prevails at the surface, with scarps and ledges 
that supplied very coarse material the ice-piled blocks are liable to be 
confused with the postglacial debris from frost fracturing of the 
jointed sandstone. As the Gilbert waters have rinsed away the 
lighter drift from the higher masses it is not easy to readily dis- 



NEW YORK STATE MUSEUM 


*52 

tinguish the ice-heaped blocks from the frost fracture piles; the 
frost work having, of course, also affected the ice deposits. 

In some places the morainal character of the drift is clearly ex¬ 
pressed by the well known features of irregular surface, mound 
and basin topography, but over most of the area the morainal ele¬ 
ment has been discriminated by one or the other of two features; 
unusually stony patches or kettles. Very stony fields with heaps of 
boulders and stone fences, specially if containing considerable per¬ 
centage of nonlocal rock, have been diagnosed as moraine. Dis¬ 
crimination is needed, for in a district of ledges, scarps or cliffs, 
specially of the quartzitic Potsdam, the ground may be strewn with 
rubbish from the native rocks which is not strictly morainal, or 
peripheral to the ice sheet, even if glacial. This criterion of stoni¬ 
ness is often equivocal and in such cases is usually disregarded. 

In districts of clayey till the occurrence of kettles or inclosed 
basins in the drift is interpreted as indicating ice margin deposits, 
and sometimes they may correlate with stony tracts. Over lime¬ 
stone floors small sinks may simulate kettles, but over the sand¬ 
stone and crystallines this deception can not occur. 

The above description will suggest how difficult if not quite 
impossible it would be to accurately map the morainal deposits over 
the entire area, and this is not attempted. The heavier morainic 
masses are shown in plates 44-47. 

Boulder moraines. Plate 47 shows the larger portion of the 
Black river moraine, which continues southwest to and beyond 
Watertown. On this map conventional signs indicate lines and 
ridges of block moraine. Some of these have high relief and are 
striking features in the landscape. One photograph is given in plate 
56. The character of the ridges as bare limestone blocks is partly 
the result of wave work of the falling waters of Lake Iroquois. 
The Black river delta built in the lake was banked against the 
moraine and partly buried its southeastern border. From the trend 
of these ridges it is apparent that the ice flow constructing them 
was from the northwest, and that the ice margin was spreading 
or deploying on the plain. 

The great massing of limestone blocks with very few crystallines 
could hardly have been effected by the earlier ice movement from 
the northeast or north, as the limestone formations do not extend 
far in that direction. The change in direction of flow enabled the 
ice to sweep up the rubbish left on the limestone tract on the north¬ 
west, and perhaps the new direction of impact, changing from south- 
westward to southeastward, gave the ice a more effective grip for 







Plate 48 



Gilbert Gulf bar south of Pine Grove hill, 4 miles northeast of Lafargeville. Looking north. Altitude about 
420 feet. Arrow, shows position of camera in plate 49. H. L. Fairchild, photo, 1908 


















Plate 49 





Gilbert Gulf beach, Pine Grove hill, 4 miles northeast of Lafargeville. View facing southeast. Altitude of 
ave work about 440 feet. Arrow shows position' of camera in plate 48. H. L. Fairchild, photo, 1908 


















GEOLOGY OF THOUSAND ISLANDS REGION 


153 


plucking on the limestone ledges; which previously had been at¬ 
tacked from the northward. 

The massing or localization of the drift, so unlike anything else¬ 
where in the southern half of our area, suggests that it was the 
accumulation produced by a readvance of the ice margin, and was 
followed by a retreat of the ice front to the latitude of Clayton, 
where the glaciers made another stand, or readvance, with accumula¬ 
tion of another belt of heavy boulder moraine (or boulder kame) in 
the Clay ton-Lafargeville-Red wood moraine. 

Boulder kames. The glacial deposits with sharpest relief and, 
outside the Black river moraine, the most conspicuous masses are 
the detached nr isolated hills of boulders and cobbles which fall 
in this class. With little attempt to classify the drift forms these 
would be called bouldery moraine, but on account of the predomi¬ 
nance of water-worn materials in the hills and on their flanks, and 
their isolation, it is thought best to distinguish them as a form 
between true moraines and typical kames. They stand out isolated, 
apart from any line or ridge of moraine, being the most striking 
hills of their neighborhoods. One known as the “ Hogsback ” lies 
1V2 miles northeast of St Lawrence and 4 miles southwest of Clay¬ 
ton and is over 100 feet high. Four smaller but conspicuous coni¬ 
cal hills lie in chain, in the line of ice flow, in esker-kame fashion, 
forming the river front of Prospect Park, west of Clayton. These 
are shown in plate .46. The same map shows the striking group 
of cobble hills 2 miles north of Lafargeville, having an east-west 
distribution and somewhat morainic aspect, which have supplied the 
materials for the best display of Gilbert bars in the entire area 
[pi. 49-53]. On the edge of this map and reaching over on the 
Alexandria sheet [pi. 47] is another prominent hill, called Pine 
Grove hill, 5 miles northeast of Lafargeville and nearly 4 miles 
southwest of Plessis. Very heavy cobble bars of Gilbert waters 
are thrown north and south from this hill, shown in plates 45, 46. 
A pit for gravel has been dug on the summit of the hill. Yet an¬ 
other hill of this kind is shown on plate 47, 24 mile northwest of 
Redwood. There is a chain of similar hills all along the north side 
of Grindstone island. 

From the large amount of rounded or water-transported materials 
in these hills, their isolation and their form and alinement, it ap¬ 
pears that they were built, at least in larger part, by torrential 
streams. And as all the area was buried under deep waters of 
Lake Iroquois during the ice waning it would appear that the 
streams must have been surficial to the ice sheet and have poured 




154 


NEW YORK STATE MUSEUM 


down the steep ice front, into the standing waters. This genetic 
relationship throws them into the category of water-laid marginal 
drift, and they are essentially kames. The inclusion of huge 
angular blocks, apparently contributed directly by the ice, along 
with the very coarse and largely unassorted materials constituting 
the bulk of the hills, proves their close contact with the ice front. 

The stony composition of these hills has been made more evi¬ 
dent by the wave erosion of the waters in which they were buried, 
the finer materials being swept away from the sloping surfaces. 
There is a general lack of clayey or adhesive material. 

The amassing of such large piles of blocks and boulders, which 
are only sparsely distributed over adjacent ground, is an interesting 
illustration of the peculiar mechanical operations of the waning 
ice sheet, which invites speculation as to the precise genetic pro¬ 
cesses. The boulder kames hold a considerable percentage of far- 
traveled fragments, Potsdam and crystallines, which argues against 
a basal position in the ice of the rock materials, in which case they 
would be mostly of local derivation. The streams which carried 
the boulders must have had high gradient, which argues for super¬ 
glacial flow. This and the unassorted structure of the conical piles 
argues for a steep frontal slope of the ice at these points. The 
glacial rivers, like land streams, doubtless had their tributaries, and 
valleys in the ice, down the walls of which the stones rolled to the 
streams; so that a river would gather up the rock rubbish from a 
large area of the ice sheet, and eventually concentrate it in a detri- 
tal cone in a notch at the ice margin. 

Kames. Deposits of sand and gravel contributed by glacial 
drainage are well displayed in a number of localities, and several 
kame areas retain their relief as hills and knolls despite the ero- 
sional and leveling action of the standing waters. Indefinite patches 
of sand are rather frequent and would be much more numerous on 
our maps if the wide stretches of country between the highways 
were all examined. 

The southernmost and earliest of the kames of the area are in 
the Black river district, shown on plate 44. Two patches lie south 
of Felts Mills, close to the limestone scarp. Small patches are 
west of Black River, and large surfaces north of Sanford Corners 
and a mile southeast. The sand plain on West creek, south of Evans 
Mills, marked on the map as correlating with Gilbert waters, may 
be partly or chiefly kame instead of delta. A kame area of de¬ 
cided relief and glacial character lies 2 miles southwest of Evans 
Mills. 


Plate 51 



cn y, 
O O 

s 

o 

^ .rj 

.M £ 

W3 .S 
<l> rt 

£ 

MJ 

• f—I « 

hr 1 
O | - L| 
O 

<u 

d ’> 
’J3 cj 

r~| 

J-H "+J 

QJ 

m c 

Ph w 


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"C 1_ 

c« ^ 


og 

4-3 O 
;-. •—1 
QJ 

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—< <D 

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O 

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Plate 52 











































































































































































































































*• 



















































Plate 53 



Gilbert Gulf shore, 3 miles west of Lafargeville. Looking northwest. Showing limit of wave work and 
removal of drift from the limestone. H. L. Fairchild, photo, 1908 



































































































































































































































GEOLOGY OF THOUSAND ISLANDS REGION 155 

Northward toward Theresa are several extensive sand tracts 
which are not covered by our maps. East of Strough is a level 
sand area of 2 or 3 square miles, traversed by the Clayton branch 
of the New York Central Railroad, which seems to have been mostly 
leveled by Gilbert waters, but which retains some kame topography 
along the railroad. Another tract is at Theresa Junction and 
eastward on both sides of Indian river, and up the river on the 
west side. Other areas occur: one 2 miles south of Strough, and 
one a mile south of Theresa. Other tracts, or extension of those 
noted above, may occur out of sight from the roads. 

On plate 46 a series of sand areas are shown extending from 
St Lawrence northeast toward Clayton, which are related to the 
Prospect Park boulder kames. Other small sand tracts are marked 
on this map, and also on plate 47.' 

Some of these sand areas have not only been modified by the sub¬ 
merging waters but have been worked on by the winds. The dune 
characters in some cases rather obscures the glacial origin. Some 
tracts are fine, clean sand, with basins or swampy intervals, like 
the Theresa Junction area. It would appear that these sands were 
laid in glacial waters over or among stagnant ice blocks; subse¬ 
quently modified by the lowering waters; and lastly acted on by 
the winds. 

Eskers. Plates 46 and 47 exhibit several series of kame knolls 
lying in definite chains in the same direction as the ice movement, 
some of them blending into true eskers. One stands on the flood 
plain of Indian river; another close to the St Lawrence river, 4 
miles southwest of Alexandria Bay; and two parallel chains 3 miles 
northwest of Lafargeville. The mapping somewhat overempha¬ 
sizes the directness and regularity of these esker-kames. The 
line of sand between the Hogsback and Prospect Park, southwest 
of Clayton, should probably he regarded as eskerlike, while the four 
Prospect Park boulder kames, and the Hogsback also, are parts of 
the chain; that is, they are all deposits made under variable con¬ 
ditions by a single glacial river. 

True eskers, gravel ridges of fair continuity and uniformity and 
lying in line with the ice flow direction, are regarded as deposits 
in the beds of full loaded glacial streams, either subglacial or su¬ 
perglacial. The true kames are the short lived deltas of the streams, 
at their debouchment. Only the streams or their deposits which 
lie in the line of the ice movement could survive. As the ice front 
recedes the kames may bury or mask the less massive upstream or 
esker ridges. 

- 


156 


NEW YORK STATE MUSEUM 


Considering their relation to the ice sheet, the kames are essen¬ 
tially morainal in so far as they are peripheral or marginal to the 
ice sheet. Eskers, specially if of great length, are longitudinal, or 
parallel to the ice movement, and correspond to drumlins of the 
ice-laid drift. The esker-kames noted above are not quite typical 
of either class, and are therefore all the more instructive. In the 
field these four or five chains are distinct and clean-cut features. 

It should be borne in mind that all these detrital deposits were 
formed when the ice front was bathed by several hundred feet of 
water of Lake Iroquois. The streams which drained the ice sheet 
may have flowed in tunnels beneath the ice (subglacial), or in 
trenches on the ice (superglacial), or rarely within the ice (engla- 
cial). To enter the standing water with sufficient force to carry 
detritus the subglacial streams must have been under considerable 
head or hydraulic pressure. 

The various differences in these water deposits must be sought 
in the variation of the glacial drainage in its complex relation to 
the inclosing ice and to the receiving waters, and to the amount 
and kind of rock debris at different depths in the ice and within 
reach of the streams. 1 

Glacio-aqueous deposits 

Clay plains. The largest in volume and the most extensive of 
the deposits due to glacial agency, direct or indirect, are the clay 
plains which were spread by the Iroquois and Gilbert waters. Ex¬ 
cept where in the Black river district the moraine and delta oc¬ 
cupy the ground the prevailing drift of practically all the terri¬ 
tory south of the parallel of Lafargeville is this clay; and also 
large areas of the lower ground north of this line. With exception 
of some till and thinly till-masked rock ridges all the lower ground 
of the Cape Vincent sheet and the southwest half of the Clayton 
sheet is clay. East of Clayton and east and west of Lafargeville 
the plains are clay, blending into till, or eastward at Strough into 
sand. Excellent views are afforded of these prairielike plains from 
rhe railroads to Clayton and Cape Vincent. In the northern dis¬ 
trict the clay occupies only the valleys and hollows, where the 

1 The reader who wishes to pursue the study of water-laid drift will find 
a philosophic discussion by R. D. Salisbury in Glacial Geology of New 
Jersey. Final Rep’t, 5:113-45. 

Kames of Central New York are briefly described by the present writer. 
Jour. Geol. 4:199-59. See also Am. Geol. 22:177-80; Am. Ass’n Adv. 
Sci. Proc. 47:278-81. 

On eskers, favoring their superglacial position, see an article by W. O 
Crosby, Am. Geol. 30:1-39. 



Plate 54 



Head of rock-walled basin of Sixberry lake, 2^> miles southeast of Redwood. Looking south. H. L. Fair- 





















Plate 55 

























Plate 56 



Boulder moraine, \ l / 2 miles west of Black River. Looking northeast, lengthwise of the ridges. Blocks are 
limestone. H. L. Fairchild, photo, 1908 
































GEOLOGY OF THOUSAND ISLANDS REGION 157 

smooth clay fillings, as meadows or swamps between the rock bluffs 
or among the rock knobs, make striking contrast [pi. 29]. 

The clay is evidently the rock flour of the glacial mill, sifted by 
the standing waters. Its glacial relationship is shown by the fact 
that in some localities it shades into ordinary clayey till; by its in¬ 
clusion of boulders and cobbles, probably ice rafted; and by its 
composition which is decidedly calcareous. 

In many exposures the clay rests directly on glaciated rock [pi. 
57] with no mass or visible layer of till or stones intervening. In 
the gullies or storm-wash hollows a few cobbles or boulders are 
commonly found, derived from the mass of the deposit, but they 
do not seem perceptibly more common at the base. The bed of 
the creek where plate 57 was taken was filled with cobbles from the 
clay ravine. At the top of this section the lamination was destroyed, 
but the crushing appears to be very localized, and has rarely been 
noted elsewhere. However, the structure does not often appear, as 
the exposed clay quickly loses its lamination and forms a rough, 
crackled skin over the slope, as shown in plate 58. It is only where 
the clays are freshly exposed that the lamination becomes evident. 

In plate 58 the numerous white fragments scattered over the 
slope are calcareous concretions, discoid or irregular in form. Evi¬ 
dently they represent concentration of the lime that was originally 
disseminated in the deposit, but the clay still retains enough of the 
carbonate to effervesce very freely in weak acid. The latter is 
true of all the clays tested, except in some cases the topping lay¬ 
ers, 1 or 2 feet thickness. The lack of carbonate at the surface 
may be due to postglacial leaching, and perhaps to original lack of 
carbonate since the latest beds may have been deposited from well 
washed material, the ice being far removed to the northward. 

Some sections do not contain the lime concretions. This is the 
case with a great exposure i l / 2 miles east of Clayton where the 
river has undercut the bank, giving a section 15 to 18 feet high. 
The lower part is beautifully laminated, the upper part with older 
exposure showing the characteristic mottled or crackled skin and 
some small lime particles. The east end of the clay section exhibits 
some crumpling of the beds. All these clays effervesce freely. 

The volume of this clay over the area increases southward, over 
the limestones, but the total seems excessive in proportion to the 
scanty drift of other materials. It is possible that the genesis and 
history of the clav is more complex than would at first appear. 
Apparently it is all Postwisconsin, for if it were partly the deposit 
of ice of earlier invasion we should expect to find the deeper and 


i5« 


NEW YORK STATE MUSEUM 


older beds of somewhat different quality, more or less crushed by 
overriding of the ice; and tills interbedded between the older and 
the newer clays. No such features have been seen. In the few 
sections observed reaching to rock the clay reposes directly on the 
smoothed rock, and the deposit is similar and homogeneous from 
bottom upward, and very finely laminated. The cases of crump¬ 
ling which have been noted are probably explicable by the ground¬ 
ing of icebergs, or perhaps by the thrust of the accumulating weight 
of clay on weaker borders of the deposit. 

An explanation of the large volume and extent of the clay seems 
to lie in the consideration of the lake conditions at the front of 
the waning ice sheet and the mechanical factors working there. 
In ordinary glacial drift or till the coarse materials remain in mix¬ 
ture with the clay (rock flour) matrix. But the agitated deep 
water in which all the deposits of our area have been laid down 
have screened out the coarse from the fine, dropping the coarse 
near the ice front, and have carried the fine material away by itself 
farther from the ice front into the more quiet water. It should 
be understood that the deposits as a whole were accumulated from 
south to north, following the departing ice front. In other words 
they grew backward. It is possible that either by lifting or by 
toppling the breaking ice kept the water agitated and so facilitated 
its sifting action. The materials contributed by the glacial streams 
were already under assorting action. Lack of strong, continuous 
currents, as rivers, or as in tidal seas, prevented the far removal of 
the silt, and the muddy waters dropped their clay burden over the 
bottom not far in advance of the ice front. Subsequently the low¬ 
ering waters scraped the silt which had been dropped on the higher 
surfaces down into the lower grounds and hollows. As there was no 
break in the existence of the standing and lowering waters, and 
consequently no pause in the depositional process, so we find con¬ 
tinuity and uniformity in the deposits. 

Pitted clays. In the hollows or basins of the Alexandria Bay dis¬ 
trict [pi. 47] are found deposits of clay which are pitted with 
basins or kettles. In some instances the silt forms merely mounds 
and ridges with intervening swales and swamps, a good example 
being seen 3 miles north of Redwood. 

These pitted clay fillings blend on the one hand into till, and on 
the other into the smooth or merely eroded clay plains. The ex¬ 
planation of their origin seems to be the deposition of the silts over 
grounded ice or anchored ice blocks. Apparently the ice masses 
were not melted until the silt deposition was ended. 


Plate 57 



Silts on glaciated rock, 2 miles southeast of Clayton, by railroad bridge. The rock is Potsdam sandstone; the 
lower part of the section is sand. The fragments resembling stones are clay masses from the upper beds. Com¬ 
pare plate 58. H. L. Fairchild, photo, 1908 


















Plate 58 


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GEOLOGY OF THOUSAND ISLANDS REGION 


159 


1 he pitted clays are a link between the ice marginal deposits and 
the open lake deposits. They might be classed with the morainal 
or peripheral drift, since they were associated with remnants of the 
ice front, but the aqueous origin is here regarded as the more im¬ 
portant element. 

Glacial erosion 

General character. The abrasional work of the glacier in this 
area is more conspicuous in the northern district where the hard- 
Precambric and Potsdam rocks are in high relief and the drift is 
mostly in the hollows. Over the southerli district where horizontal 
limestones form the floor the ice erosion was probably greater than * 
farther north, but the evidences are more concealed. The origin 
"of the plains, plateaus and mesas, by preglacial weathering, glacial 
planing and stream trenching, has been discussed in a former chapter 
[p. 146]. 

The more vigorous erosion on the limestones is shown by flutings 
or ribbing, the lighter and later, by striation and polish. The Pots- 
^dam and crystalline knobs seem to have been little more than “ sand¬ 
papered ” by the latest glaciation. The broader surfaces of the 
more horizontal Potsdam shows effective abrasion in spots only. 
The impression made on the observer is that glaciation of an earlier 
ice invasion was vigorous but that the latest ice sheet was compara¬ 
tively ineffective. 1 

Striations. Occurrence. The limestones exhibit few striae, 
as will be inferred from the lack of arrows on the maps of the 
limestone districts [pi. 44-47]. It is uncertain whether this should 
be chiefly attributed to the failure of the latest ice to generally abrade 
the rock surface, due possibly to clayey character of the subglacial 
drift in this district, or to the obliterative effect of solution and 
weathering. The limestones are readily attacked by atmospheric 
waters, as proven by the very numerous areas of solution structures 
and open joints [p. 133, pi. 26-27, 35]. But in many places the 
fresh removal of clay or clayey till that would seem to be sufficient 
protection to the rock reveals unglaciated surface, though usually 
firm and even, as if a glaciated surface had lost its .smoothness. This 
feature is emphasized by the finding in the same locality surfaces 

1 Unfortunately we have no standard or measure of the intensity of ice 
abrasion or erosion, or glaciation in general. When a writer says that the 
drift is scanty or abundant, that erosion has been great or small, he ex¬ 
presses merely his own conception of relative intensity, based on his obser¬ 
vational experience. It is apparent that different observers might have 
different opinions, according to the range of their work and their mental 
attitude. Moreover, the view of the same student might vary with increas¬ 
ing experience and changing emphasis on the various elements or factors. 



l6o NEW YORK STATE MUSEUM 

recently exposed with perfectly preserved polish. While it is 
possible that this difference in surface characters may be the effect 
of differences in present conditions of drainage and solution, though 
improbable, it seems more likely that we have here another illustra¬ 
tion of multiple ice work. 

In the Potsdam areas the impression is given of general ice 
abrasion by the frequent patches of polish and striae; but the un¬ 
scored surfaces far outnumber the striated. Idere, again, we have 
the uncertainty as to the degree of weathering and destruction of the 
latest glacial records, because exposed surfaces, apparently of iden¬ 
tical quality of rock and equality in exposure exhibit partly highly 
polished and partly unscratched surfaces. The fact of a general 
grinding and smoothing of the rock is clear, but quite certainly not 
by the latest ice sheet. 

Direction [see pi. 44-47]. Near the St Lawrence the average 
direction of striae is about parallel with the river. Leaving out the 
extreme and aberrant marks they may be generalized as follows: 
at Chippewa Bay, s. 25 0 w.; Alexandria Bay, s. 25-40° w.; Clayton, 
s. 40-50° w.; eastward from the river and from the axis of the val¬ 
ley the striae are more variable and swing more southerly. About 
Redwood some striae are s. 40° w., probably representing the 
stronger flow of the deeper ice, but a great number range within 
s. 10-20° w. About Theresa the greater number lie within s. io° w. 
and s. io° e. East of Chaumont the striae are s. 35° e.; at Evans 
Mills, 10-20° east of south and at Sanfords Corners, 30° east of 
south. The Leraysville moraine [pi. 44] clearly shows the south¬ 
easterly push of the latest ice in the district. This easterly swing of 
the ice in the eastern part of our area was due to the well known 
spreading or radial flow of a lobation in the ice front. As the ice 
sheet waned the last portion resting over the area was a broad lobe 
occupying the St Lawrence depression and having spreading flow 
toward the east side of the valley. Along the east side of our maps 
the most westward striae represent the general direction of the maxi¬ 
mum flow while the eastward striae are later scratches by the ice 
margin. 

Curved scorings. A remarkable example of curved scorings 
may be seen on a broad, flat, smoothed surface of Potsdam sand¬ 
stone 2J/2 miles east-southeast of Alexandria Bay, about y 2 mile 
west of three corners. The bare area lies in the track and on the 
north side of an abandoned highway, on land of John Bogert. The 
locality is indicated by three converging arrows on plate 47, and one 
photograph is given in plate 59. 


Plate 59 



Curved glacial scorings on planed Potsdam sandstone, 2^ miles eastsoutheast of Alexandria 
Bay. Looking downstream, south 56° west. The scorings curve to south 44 0 west. H. L. Fair- 
child, photo, 1908 





























GEOLOGY OF THOUSAND ISLANDS REGION l6l 

A considerable area of planished rock is covered by striae which 
have various directions, from s. 56° w. to s. 16 0 w. Apparently the 
markings with the more westerly trend are the older and prevailing 
ones over most of the surface, the later and more southerly abrasion 
having softened the older groves and given a cross polish. But the 
later motion is also represented by a few strong chatter bands which 
quite obliterate the older scorings where the latter are crossed. 

The curved markings lie in a belt about 10 feet wide and over 50 
feet in length now exposed. The scorings are strong, clean-cut, 
and perfectly parallel. At the north end they lie for several yards 
perfectly straight, with direction 56° west of south, then they gently 
curve, southing with steady uniform curvature until the direction is 
s. 42° w. The curving is still continued where the belt of scorings 
passes under the turf on the south side of the wagon track. The 
strong furrows may not be confidently traced throughout the entire 
length of the curve in distinct individuality, as later abrasion has 
somewhat obscured them in places, but they are practically con¬ 
tinuous and retain their relation and character. The belt of curved 
scorings is exceptional to the general striae of the broad surface and 
surrounding bare patches, the prevailing direction being s. 30-35 0 w. 

The curving lines have no angularity and show no hesitation nor 
pauses or spasms in the ice motion. In one place a few of the 
strong scorings in a narrow strip exhibit a perceptible variation 
from the true curvature, or a tendency to straightness, but taking 
the belt as a whole the curvature and the parallelism of the lines 
appear to the eye to be true. The radius of the curve is about 60 
or 70 feet. The chord of the exposed belt, including about 15 feet 
of the straight beginningof the scorings, is 54 feet; and the ordinate 
is 23 inches. 

This glaciated surface is the northern side of a broad rock plain, 
with no apparent cause in the surrounding topography for the de¬ 
flection in the ice flow. A narrow valley lies near on the north, 
across which is a somewhat higher plain. The map, plate 44, shows 
the general topography. 

A significant fact is that the curving belt of scorings, even at the 
southern deflected end, so far as uncovered, is much more westerly 
in trend than the prevailing ice movement, not only in the immediate 
locality but in the great area. 

Chatter marks and gouges. The innumerable exposures of 
the Potsdam sandstone, often of large extent, coupled with the very 
hard and brittle texture of the rock, furnish many excellent ex- 


NEW YORK STATE MUSEUM 


l 62 

amples of the effect of the dragging pressure and the percussive 
force of the boulder-shod ice. The rock is too hard to accept much 
furrowing or mass removal on the flat surfaces, but its brittleness 
favors the production of fractures due to compression and to strik¬ 
ing force. Of these features two classes will be briefly described. 

The hard boulders held as planes and hammers in the bottom ice 
have produced two kinds of curving fractures, one class convex up¬ 
stream or toward the boulder, the other convex downstream or con¬ 
cave toward the boulder. Those with the concavity facing down¬ 
stream, that is to say, with the convexity toward the producing tool, 
fall under the category of “ cones of percussion ” or “ chatter 
marks.” Many excellent examples of these concentric fractures are 
seen, some of large size or up to 10 inches of arc and forming from 
one quarter to one third of the circle. Sometimes the parallel con¬ 
centric fractures are closely crowded, several within an inch, but 
are usually somewhat more open, three or four or less to the inch. 
Figure 13 is traced from a “ rub ” taken by the road near the house 



Six Inches 

Fig. 13 Chatter fractures 

of William Northrup, 3 miles northwest of Redwood and 3 miles 
east of Alexandria Bay, and about 24 of a mile northeast of the 
curved scorings described above. In this case 11 fracture lines lie 
within 4 inches along the axis of the curvature, most of them being 





GEOLOGY OF THE THOUSAND ISLANDS REGION 1 63 

short. The longer lines have an arc of 6 inches or a radius of about. 
3inches. 

Another excellent illustration of the chatters is on the highway 
3 miles north of Redwood on the road to Chippewa Bay, at the point 
indicated on plate 47. Several very large examples occur in 
the middle of the street in Redwood village, just below the Dollinger 
House. Smaller examples are so very numerous that no notebook 
record was made of them. Fine examples occur with the curved 
scorings. 

1 he chatter fractures dip so steeply into the rock that rarely is 
there any flaking of the surface rock. In many instances no axial 
grooving or crushing of the rock is visible, the appearance being 
as if the rock had been abraded and resurfaced and polished so as 
to leave merely the clean-cut concentric fracture lines. Such 
abrasion is more than possible but is very slight, as early striae hav¬ 
ing the direction of the axes of the chatters are not obliterated. 
Commonly there is some evidence along the axial line of the pres¬ 
sure by the unsteady or chattering tool. 

The other class of fractures, having the concavity facing upstream 
toward the tool, are much less regular or true than the chatter frac¬ 
tures. In both classes the cracks dip downstream or away from the 
point of the tool, but in these gouge fractures the angle of dip is 
much less than in the chatters, and commonly there is considerable 
flaking of the rock or removal of the feather edges of the surface 
rock. These cracks fall in the class of “ concentric gouges ” or 
“ disruptive gouges ” of earlier writers. 1 The action seems to have 
been a sort of drag or pull on the surface of the rock by pressure 
of a boulder with broad area of contact, but without pounding or 
percussive force. The process was a plucking by dragging pressure. 

These gougings are not as common as the chatters, and only two 
good localities were noted. One of these is Y\ mile south of the 
county line between Jefiferson and St Lawrence counties, on the west 
road to Chippewa Bay. The other occurrence is on the road east of 
Goose bay and on the south side of Crooked creek valley. The 
first mentioned is on the south end of a plain, the latter on a sur¬ 
face facing north, where the ice was pushing against an upslope. 

The gouge fractures are rarely true circular curves, in which cases 
they may be mistaken for chatters, but commonly they are irregular 

1 A full description and discussion of these singular phenomena con* 
nected with glacier mechanics is given in Professor Chamberlin’s paper 
Rock Scoring of the Great Ice Invasion. U. S. Geol. Sur. An. Rep’t 1888. 
p. 216-40. Reference to other writings is there given. 

6 



164 


NEW YORK STATE MUSEUM 


in both form and relation. They lack concentric parallelism, in 
other words are not in regular series; and they are not always 
transverse or normal to the line of motion of the tool, as shown 
by the band of crushing or gouging. Figure 14 shows these 
characters. 

To summarize: the gouge 
or dragging fractures would 
seem to be . the effect of a 
steady dragging motion of a 
boulder with large contact sur¬ 
face, while the chatters are the 
product of unsteady, percus- 
-H sive or pounding movement of 
points of boulders or small 
contact surfaces. 

Limestone flutings. Over 
large districts in the southern 
part of the limestone area the 
Fig. 14 Gouge fractures rock surface is worn into series 

of parallel, cylindrical ridges of several feet diameter, separated by 
equally regular troughs or hollows. These features which can be 
attributed only to ice erosion are illustrated in plates 60-63. As the 
amount of erosion and the direction of the ribs and ice movement 
are inconsistent with the work of the latest ice sheet the discussion 
of the topic is deferred to the next chapter. 



Prewisconsin glaciation 

Theoretic considerations. In the preceding pages several 
features have been mentioned as difficult of explanation or incon¬ 
sistent with the conception of a single ice invasion. The facts 
and argument favoring the view of multiple glaciation will be 
summarized here. 

If the generally accepted conclusions of glacialists, that the north¬ 
eastern states have been repeatedly glaciated since Tertiary time, 
are well founded, it is quite impossible to except or exclude 
New York from all ice invasions earlier than the latest, or Wis¬ 
consin. The several glacial epochs recognized in the Mississippi 
valley have been named on page 137. The very old drift of New 
Jersey and southeastern Pennsylvania is believed to be as old, cer¬ 
tainly, as the Kansan, and probably represents the Preaftonian, 
which is now sometimes called the Jerseyan when referring to the 





GEOLOGY OF THOUSAND ISLANDS REGION 165 

\ • 

eastern region. I he drift of northwestern Pennsylvania lying in 
advance of the Wisconsin drift, is believed to be as old at least as 
the Kansan. For an ice sheet to so expand as to reach either 
northwest or southeast Pennsylvania without trespassing on New 
York seems impossible. Hence we are forced to the belief, apart 
from any evidences on the ground, that the State has been more 
than once in the climatic condition of Greenland at the present 
time. 

If the State has been overrun by ice sheets more than once it 
seems rather strange that geologists have not recognized the phe¬ 
nomena and discriminated the records. It must be admitted that we 
now lack the evidence afforded by multiple till sheets, separated by 
temperate climate deposits such as are found in the Western States. 
W ith attention directed to this subject it is probable that some con¬ 
clusive proofs will be discovered. 

But while no single fact or class of phenomena yet found fur¬ 
nishes conclusive proof of more than one ice epoch, we have a 
variety of indirect evidences, and many features are well ex¬ 
plained only on that supposition, and several lines of study converge 
toward that conclusion. Moreover, to attribute all the glacial 
phenomena to a single ice sheet involves inconsistencies, such as 
the evidence of impotence in erosion of the latest ice, with indica¬ 
tion of vigorous erosion formerly; and the lack of glaciation sur¬ 
faces on ice-shaped rock as well protected as places showing hairline 
striae and polish. 

The glacial features of the Thousand Islands region which are 
not satisfactorily referred to the latest ice work probably can not 
be attributed to an ice sheet as ancient as the Kansan, but would 
seem to be the effect of some recent ice epoch. Whether it was 
one of the later Prewisconsin invasions or only an early Wis¬ 
consin episode we may not now decide. 

Anomalous physiography. South of our area, in the central 
part of the State, many channels of ancient drainage are found 
which are not Postwisconsin. In the area under discussion these 
features do not occur because the whole region was drowned in 
deep water during the ice recession. But the region has its own 
peculiar topographic features that are difficult of full explanation 
under the conception of a single ice transgression. The valley, 
basin and scarp topography has already been briefly discussed 
[p. 146]. Other points will be touched on below, but a full dis¬ 
cussion of the difficult problem requires more fieldwork specially 
directed to the particular features. 


166 


NEW YORK STATE MUSEUM 


Old till. As far as the writer is informed, the first one to 
recognize PreWisconsin till in New York was F. B. Taylor. In the 
summer of 1905 he directed attention to the very compact, resistant, 
stony, blue till in the bottom of the deep valleys southeast of Buf¬ 
falo, which he confidently pronounced older than the overlying and 
prevailing Wisconsin drift. Subsequently the writer noted other 
occurrences of similar till. In 1907 Frank Carney published an ac¬ 
count of what he regarded as old till in the Keuka valley. 1 

No soil zones or forest grounds lying between the supposed old 
till and the superfical till have yet been found, to prove the fact of 
an interval of deglaciation, though such finds may be expected. 
The writer has noted very sharp distinctions between the two tills, 
with incorporation of the lower into the upper. An important 
locality is along the new cuttings for the shortened tracks of the 
Delaware and Hudson Railroad west of Schenectady, between Kelly 
station and Duanesburg. Here an incoherent, yellow till, capped 
with gravel, directly overlies a very hard, dark blue till. The con¬ 
trast between the two is very striking and the line of separation is 
very distinct in some sections; while in places the older blue till 
has been plowed up and masses have become incorporated in the 
yellow till. The blue till retains its color and consistency even when 
exposed for considerable time to the weather, masses which have 
lain in the field over the winter being only partially disintegrated. 
The writer was told that the steam shovels were able to cut the 
blue “ hardpan ” with much difficulty and very slowly. 

The blue t : ll has a very different composition and derivation 
from the overlying and oxidized yellow till. It is impossible that 
an ice sheet, producing from its burden of ground-up shale and 
limestone the hard blue till, should suddenly cease to deposit this 
and at once lay down a yellow oxidized till of entirely different 
origin. We have here good proof of at least two distinct episodes 
in ice work. 

The writer has not noted in our Thousands Islands area any 
example of tills comparable to the old, blue tills farther south, 
though Cushing thinks that he has seen them. But they probably 
do occur just south of the boundary, in the northern part of the city 
of Watertown. Here begins a group of drumlins that extends 
southward. In the mass of the drumlin forming the dome-shaped 
hill north of the Black river, and in the small drumlin ridge in the 
northwest corner of the city, where the Dexter electric line crosses 

1 Pre-Wisconsin Drift in the Finger Lake Region of New York. Jour. 
Geol. 15:571-85. 



Plate 60 



Postglacial weathering. Open joint across limestone ribs, 1V2 miles east of Dexter. Looking northwest. H. L. Fair- 
child, photo, 1907 


















GEOLOGY OF THOUSAND ISLANDS REGION 


167 


the Cape Vincent branch of the New York Central Railroad, a 
hard, gray blue till appears that is very unlike the prevailing drift 
of the northward area. The latter exposure is shown in plate 52. 
The resemblance of this drumlin till to the “ old ” tills farther south 
is as close as might be expected when the differences in latitude, 
source of the material, etc. are considered. However, we must 
recognize that the drumlin till was subglacial, deposited beneath the 
ice and under tremendous grinding pressure; while the surficial 
drift of the area was dropped in standing water, and is conse¬ 
quently incoherent, sandy, inclined to yellow or gray colors, and 
carry few striated or abraded stones. The production of masses of 
subglacial drift or drumlins is a sort of work which the later ice 
did not do north of Watertown, at least to noticeable extent, and 
it is doubtful if it did such work at Watertown. However, the 
drumlin till is inconclusive, until we know if the Watertown drum¬ 
lins are the work of the latest ice or of some earlier invasion. 
This Watertown till is not in valley bottoms or deeply buried, but 
in hills above the levels of the plain. 

Limestone ribbing. Over the southern part of the Clayton 
quadrangle the limestones frequently exhibit series of parallel ribs 
or flutings, a sort of washboard structure on a vast scale [pi. 60-63]. 
These ribs positively have no genetic relation to the joint structure 
of the rock. They are pronounced convexities, often quite cylindri¬ 
cal but commonly rather flat, with a breadth from crest to crest, 
or across the base, from 2 to 10 feet; the usual breadth being 3 to 
5 feet. The hollows between the ribs are usually filled with drift 
or soil, but when cleared they show quite cylindrical troughs of 
uniform width and fair curvature, and parallelism with the ribs. By 
solution-weathering the sides of the flutings are rarely steepened 
and the bottoms perforated by solution holes, as in plate 63. 

Within any single exposure these flutings are strikingly parallel 
[pi. 61] and are approximately so over the whole region, having 
a direction about s. 45 0 w. Scores of them have been measured with 
that direction, over all the area between Dexter and St Lawrence 
village. The extreme variation in direction is s. 40° w. for the 
heavy ribbing east of Dexter, and s. 50° w., south of Dexter, shown 
in plate 63. Two other localities toward St Lawrence gave the 
latter compass direction. 

Speaking broadly the flutings have lost all their glacial surfaces, 
retaining only the erosional form, for their origin by ice erosion of 
the limestone seems certain. In a very few cases a suggestion of 
the heavier scorings are preserved, and some minor flutings on the 


168 NEW YORK STATE MUSEUM 

ribs. The ribs which have been long exposed have been so corroded 
by weathering that one might question even their glacial origin. 
But those flutings also which are only recently uncovered have lost 
their glaciated surface, though they may show the perfect polish of a 
later glaciation oblique to the ribbing. This fact is important with 
reference to the age of the ribbing. 

In plate 61 we see a typical example of the ribbed limestone, the 
locality being the west side of a hollow several rods-west of the rail¬ 
road station at Threemile Bay. The ribbing is s. 45 ° w. The three 
ribs in the foreground at the lower right corner have been strongly 
cut and polished by an ice flow having direction s. 55 0 w. This 
change of 10 degrees in direction is not unusual for the same ice 
sheet, and taken alone would be weak evidence of dual glaciation. 
The important fact here is that the later ice movement has scored 
and polished the ribs obliquely, striking them on the east faces, 
and the later polishing is perfectly preserved though apparently has 
been exposed as long as other portions of the ribs where no glaci¬ 
ation is visible. The ribs are being freshly uncovered by the wash 
on the slope, but the only glaciation seen is that oblique to their di¬ 
rection. The only reasonable inference is that the ribs have lost 
the glacial surface by old age weathering and that the oblique polish 
is from a later ice rubbing. The ribs are rough and corroded where 
not cut by the more westerly planing, and it is certain that the lack 
of striae and polish on the ribs can not be due to merely recent 
weathering. 

The ribs and hollows have no fixed relation to the joints of the 
rock. In the locality of plate 61, while the ribbing is s. 45 0 w., the 
joints, so far as they have any dominant trend, are s. 75-85° w. 
Nowhere are the joints so true and parallel as the ribbing. Only 
occasionally do joints appear in the furrows but they commonly 
lie boldly across the ribs and are frequently opened widely, as in 
plate 60, where some joints are a foot wide and 10 feet deep. The 
removal of the clays of the latest deposits from the ribbed sur¬ 
face shown in plate 60 has been chiefly by subterranean drainage 
through these open joints. It seems very unlikely that these open 
. joints were produced with their present size and form since the last 
glaciation and beneath several feet of the Dexter clay [pi. 58]. 
The joints certainly are the product of atmospheric weathering 
and solution, and it seems a safe inference that they represent a 
time of long exposure antedating the last ice work. 

These exposed ribs east of Dexter, visible on the north side of 
the electric line, lie in a hollow in the clay, as shown in plate 63, 


Plate 61 



/ 


Glacial ribbing in limestone, Threemile Bay station. Looking north 35° east. Compare plates 62 and 63. 
Direction of ribs s. 40° w. Recent glaciation in lower right corner, s. 55° w. H. L. Fairchild, photo, 1908 













Plate 62 



Weathered rib of limestone, i l / 2 miles west of Brownville, south side of Black river. Looking southwest. 
Compare plates 61 and 63. H. L. Fairchild, photo, 1908 











Plate 63 



Glacial flutings in limestone, mile southeast of Dexter. Looking n. 50° w. Compare plates 61 and 62. Directions 
of ribs s. 50° w. H. L. Fairchild, photo, 1908 











































































































































































































































































































GEOLOGY OF THOUSAND ISLANDS REGION 169 

the hollow being produced partly by the washing of the clay cover 
down the wide solution joints. On the sides of the hollow the ribs 
are being newly uncovered by the storm wash and the tramping 
of cattle, but no trace of glacial polish was seen, the new surfaces 
being similar to the longer exposed surfaces of the middle of the 
ribs. Masses of chert standing 2 or 3 inches above the limestone 
surface prove a long period of solution of the rock surface, which 
seems impossible beneath the present clays in the short time in¬ 
volved. Enforcing this conclusion is the fact that only a number 
of rods distant, in the gutters of the electric road under similar clay 
cover the same limestone shows elegant glaciation. But while the 
ribbing is s. 40° w. the preserved glacial scorings are variable, rang¬ 
ing from s. 50° w. to s. io° e. 

These two examples of the ribbing, which can be multiplied, will 
•give illustration of the quality of the evidence they offer in favor 
of at least dual glaciation in recent time. These flutings are wide¬ 
spread, remarkably uniform in direction (generally s. 42-45 0 w.), 
symmetrical and true in form. They can not be attributed to 
weathering, nor jointing, nor wave work, nor water corrosion, all 
of which have left conspicuous records in the district. Undoubtedly 
the ribbing is old glacial, and it represents a glacial abrasion vastly 
more energetic than the similar work of the latest ice sheet. 

Weathered surfaces. The considerable weathering which the 
limestones have suffered is shown in plates 23, 26, 27 and 63. 
Doubtless some part of this corrosion is postglacial, specially on 
the more exposed patches and on cliff edges where the rock was 
not buried by the drift; but it must not be assumed that these 
etched, corroded and open-jointed surfaces were all left smooth 
and glaciated by the latest ice sheet, as that is the question under 
discussion. 

The uncovering of corroded surfaces which have been under 
clay that would seem to have been sufficient protection from the 
postglacial weathering, as illustrated in plates 61 and 62, argues 
strongly for nonglaciation of such surfaces. The conditions shown 
in plate 60 seems to prove that great open joints existed in the 
limestones previous to the deposition of the glacial clays. • 

Probably many of the deeply corroded surfaces were recently 
buried under ice or lake deposits which have been swept off by 
the wave erosion of the standing waters and the subsequent and 
now acting storm wash. Without more special study on the ground 
it is impossible to estimate the amount of postglacial weathering. 
In some places it seems very small, and where slightly covered prac- 


170 


NEW YORK STATE MUSEUM 


tically nothing. Such cases give the impression of slight corrosion 
since the ice removal. On the other hand the existence of broad 
surfaces of exceedingly rough and open-jointed rock, from which 
the farmers have to fence their cattle, and the location of which 
would seem to have been favorable to glaciation, give the suggestion 
of large postglacial weathering. The critical question is, were the 
latter surfaces glaciated by the latest ice sheet? It would appear 
that a duration and intensity of postglacial weathering which has 
not destroyed the glacial polish on the limestone ribs shown in 
plate 61 could not justly be held responsible for the open joints 
and rough surfaces shown in plate 60, where a deep clay cover has 
been removed chiefly by washing down into the open joints and 
being carried away by subterranean flow. 

The amount of recent weathering is conspicuously greater in 
locations where the surfaces have been subjected to wave wash of 
the Iroquois and Gilbert waters, this being specially effective in 
both solution and mechanical removal of the limestone. 

Old planation surfaces. If the ribbing on the limestone was 
in existence before the last ice invasion then, of course, the lime¬ 
stone plains and plateaus were formed previously; and it has al¬ 
ready been stated that the broader topographic features are con¬ 
fidently believed to antedate Wisconsin glaciation. An ice sheet 
with sufficient vigor to do the plucking and planing necessary to 
give the limestones and Potsdam sandstones their breadth of flat¬ 
ness should leave abundant evidence in glaciated surfaces; and the 
limestone ribbing is a relic of such effective erosion. Again, the 
general lack of glacial polish is the fact which requires explanation. 

The plains of Potsdam sandstone present the same question. 
Over broad surfaces of the very firm, hard, insoluble sandstone, 
either bare or practically unprotected by any impervious cover, only 
a minor part exhibits striae or polish. Certainly it was once all 
vigorously glaciated, for in no other way could the level, even, firm 
surfaces be produced. From hasty examination it is impossible to 
confidently decide whether the patchy scoring and polishing is due 
to weak recent glaciation on an old weathered surface, or to reten¬ 
tion of polish under present weathering. The former alternative, 
recent partial smoothing on an old weathered surface, is more in 
harmony with the general body of fact; and it seems more prob¬ 
able that the recent ice sheet failed to generally polish the old 
weathered surface than that patches with finest polish and hairline 
striae should be so perfectly preserved while surrounding surfaces 


GEOLOGY OF THOUSAND ISLANDS REGION 171 

with apparently identical physical conditions have lost all traces 
of recent glaciation. 

Weak erosion of the Wisconsin ice sheet. It will be seen that 
the critical point in this study is the erosional impotence of the 
latest ice sheet. With this established then at least dual glacia¬ 
tion of the region must be accepted. 

The principle is recognized by glacialists that intensity of ice 
erosion depends on pressure, velocity of the bottom ice, and its 
armament or tools. The glacier can do its most effective work of 
abrasion when the basal ice is only moderately charged with rock 
rubbish, and that of hard texture. A heavy burden of subglacial 
drift serves to diminish the plasticity of the ice and so reduce the 
velocity of flow; while at the same time it acts as protection or a 
buffer for the subadjacent rock. For this reason rapid corrasion is 
a self-checking process. 1 On the other hand it is certain that clear 
ice can not abrade the bed rock at all. A moderate load of hard 
tools is the most effective for abrasion. 

The first ice sheet that transgressed our region found it deeply 
covered with the residual product of millions of years of weather¬ 
ing, and could do no effective erosion until not only the sheet of 
geest (regolith) on our area had been removed but also that lying 
on the region northward into Labrador and Canada which was 
swept by the southward ice flow. The theoretical stages would 
be as follows l (i) the scraping away of the decay product and 
bearing it far southward, as no very heavy moraines lie near our 
area; (2) vigorous erosion during the phase of favorable load, 
with harder tools from the plucking of the fresher rocks; (3) 
weak abrasion by the clearer ice after the glacier had swept its 
floor and reduced the asperities in its path. 

On the postulate of a single ice invasion of the Thousand Islands 
region it is necessary to assume that after the ice had removed 
the abundant product of Prepleistocene weathering it used its 
medium load of debris to plane the hard Potsdam and to plane and 
deeply flute the limestone, but at the same time failed to rub down 
the scores of comparatively abrupt cliffs and scarps which opposed 
its motion. Here we find another inconsistency. Without further 
discussion it will be understood that the assumption of a single 
glacial epoch involves serious contradictions and difficulties in the 
explanation of the phenomena of the region. 

Assuming dual or multiple glacial epochs the features and history 
are fairly clear. The accumulations of long efas of rock weathering 


1 Geol. Soc. Am. Bui. 16:26. 



NEW YORK STATE MUSEUM 


172 

were swept southward by the earlier glaciation. Later ice work 
with more abrasive power planed the harder stratified rocks, grooved 
the limestones, modified the topographic forms by softening the 
scarps and rock knobs and straightening the drainage lines. One 
or more long interglacial epochs partially restored the character¬ 
istic atmospheric-erosion forms of the Theresa and Pamelia scarps 
and cuesta fronts; reexcavated the valleys and basins; and de¬ 
stroyed the surhcial glaciation on the sandstones and limestones. 
The latest ice sheet finding the northward region denuded of rock 
debris and smoothed by the earlier glaciation was unable to arm 
itself for effective erosion and thus handicapped was competent only 
to weakly abrade in places. It is possible that while the deglacia¬ 
tion interval in our district produced some weathering effects the 
northward (Labrador) region was continuously snow-covered and 
the ice was not able to pluck a new supply of granitic tools. 

• Undoubtedly there were important differences in the behavior 
and mechanical effects of the several ice sheets, due to differences 
in rate of accumulation and velocity of flow; of depth and pressure; 
of temperature and rate of waning; and these combined with, and 
an effect of, climatic variations. 

It would have been entirely proper in this writing to have as 
sunned multiple glaciation and confidently to have explained the 
singular features of the area on that basis. Perhaps the method 
of argumentation which has been used is somewhat confusing to 
the reader, but he will better appreciate the complexities of the 
study and its consequent fascination. 

ECONOMIC GEOLOGY 1 

While the district under consideration is bordered on the east 
by an area in which hematite, pyrite, galena and talc have been, 
or are being, mined, none of them have been found in anything 
like workable quantity within the limits of the map. -The fer¬ 
ruginous quartz schists of the Grenville are present in quantity but 
are very lean ores indeed. One mile north of Theresa on the Red 
lake road a small opening has been made on a hematite mass which 
occurred as a direct replacement of Grenville limestone. The ma¬ 
terial was a finely crystalline, scaly, specular iron, and was of great 
purity, but there were only a few tons of it. While therefore the 
deposit was of interest as a clear and pretty example of replace¬ 
ment of the sort, it had no economic value. 


1 By H. P. Cushing. 



GEOLOGY OF THOUSAND ISLANDS REGION 


173 


Small masses of barite are not infrequent in the Grenville lime¬ 
stone, but none were seen of any size or importance. An old 
opening was made on a coarsely micaceous limestone contact zone, 
2 miles north of Theresa, but no mica of merchantable size and qual¬ 
ity was forthcoming. 

The only mineral industry of the district that has any present or 
prospective value is the quarry industry. Stone has been and is 
being quarried for road metal, for paving, for flagging, for lime, 
and for construction. Various Precambric rocks, the Potsdam 
sandstone, and the Pamelia, Lowville and Black River limestones 
have all been quarried in varying degree for one or the other of 
these purposes. 


Road metal 

Road improvement is going on hereabout, as elsewhere in the 
State. About Theresa, Grenville limestone has been chiefly used, 
though a small quarry has been opened in very impure limestone 
cut up by granite, which furnished very variable, and hence not 
very good material. The limestone from the other quarry makes a 
very good macadamized road, as would apparently much of the 
Grenville limestone of the district. 

About Alexandria bay various experiments have been tried with 
road metal. The Laurentian granite gneiss of the vicinity has been 
used, and of course given poor satisfaction. To a small extent 
Pamelia limestone has also been used, and has not proved very 
satisfactory, probably because of the variability of the different 
layers used, pure limestone and magnesian limestone probably being 
mixed together. At present a considerable stretch of road north 
of Browns Corners is being macadamized with Grenville amphib¬ 
olite, obtained 1 mile west of Redwood, surfaced with Grenville 
limestone, which, as we saw it being obtained, was of poor qual¬ 
ity. The amphibolite was slightly soaked with, and cut by granite, 
so that the material was not as uniform as is desirable, but the 
quantity of granite is so slight that the lack of uniformity is not 
prominent, and the amphibolite itself is quite undecayed, firm and 
strong. It seems on the whole likely to prove quite adaptable to 
road-making purposes. Its composition is quite similar to that of 
trap, and in all probability it will bind in similar fashion. 

Potsdam sandstone has been used as a road rock to a small ex¬ 
tent. It is absolutely unfitted for such use, and the worst rock that 
could be selected for the purpose. 


i74 


NEW YORK STATE MUSEUM 


In the southern part of the mapped district the Lowville, Black 
River and Trenton limestones have been used on the roads, and 
all serve the purpose very well. 

The rock of the district best fitted for road metal has, as yet, not 
been utilized at all, namely that of the trap (diabase) dikes. There 
is no better road metal known than trap, provided it be unrotted, 
and the wide dikes which occur on Grindstone island are capable of 
furnishing a considerable supply of material, much of which is cer¬ 
tainly quite fresh. The material is in large demand for road-mak¬ 
ing purposes. 

On the country roads to the eastward of Alexandria Bay, on which 
travel is light, the easily rotting, aluminous phases of the fer¬ 
ruginous quartzite (Grenville) have had considerable use for sur¬ 
facing the roads, and answer the purpose satisfactorily. 

Granite quarries 

During the past season both the Picton granite and the Lauren- 
tian were being quarried in the district. The former rock has been 
intermittently quarried on Grindstone island for a number of years 
and has been considerably used for structural and ornamental pur¬ 
poses, both locally and -at a distance. For uses for which pro¬ 
nouncedly red granites are serviceable it compares very favorably 
in appearance and quality with the other red granites of the country. 
There is much quite uniform material available, and large sized 
blocks can be quarried. In 1908 none of the Grindstone island 
quarries were being worked, though quarrying was actively in 
progress on Picton island, where the chief quarries of today lie. 

On the mainland, a short distance west of Alexandria Bay, active 
quarrying operations are in progress in the Laurentian granite 
gneiss. At the location the rock is fairly uniform and free from 
inclusions, and is being quarried for paving blocks, which are being 
shipped to Chicago for use. Transportation to the various cities 
on the Great Lakes is of course cheap, and the rock seems well 
adapted to the purpose for which it is being used. 

Sandstone quarries 

Various small openings have been made in the Potsdam sandstone 
here and there in the district, for very local building and flagging 
purposes. Just beyond the Alexandria sheet edge, to the east, in 
the town of Hammond, the Potsdam forms a long scarp, at the 
base of which the railroad runs, and the rock here is quarried largely 


GEOLOGY OF THOUSAND ISLANDS REGION 175 

for paving blocks. It is fairly evenly and thinly bedded here, mostly 
of red color, well indurated, and quite well adapted to the pur¬ 
pose. The same would be true of much of the Potsdam of the 
adjacent portion of the Alexandria sheet, were it as conveniently 
situated as regards transportation. 

Limestone quarries 

There are many of these in the district, quarrying the Pamelia, 
Lowville and Black River limestones, both for structural purposes, 
and for burning for lime. The massive 7 foot tier of the Black 
River is largely quarried, the large solid blocks obtainable render¬ 
ing it an exceedingly serviceable material for heavy masonry con¬ 
struction, much more so than the thinner bedded Lowville and 
Pamelia limestones. Some of the beds of the upper Lowville are 
also fairly thick, make very serviceable stone where construction is 
less massive, and hence are quarried in many places. Most of the 
Pamelia is much thinner bedded, and the thicker beds are mostly 
separated from one another by much thin bedded material. Never¬ 
theless the formation contains some good stone, and there are 
numerous quarries in it all the way from Leraysville to west of 
Clayton, which, however, chiefly serve a local use in the northern 
part of the mapped area. It is not so largely quarried and used 
as the upper Lowville. The dove limestones of the upper part of 
the formation should, it would seem, make an excellent cement rock. 

A single quarry has been opened in the impure, thin beds of the 
upper division, a few miles south of Clayton, and the stone used 
for flagging in Clayton. Owing to the joints only medium sized 
slabs can be obtained, but otherwise the rock is fairly smooth sur¬ 
faced and makes a very respectable flagstone. 

The quantity of limestone in the district available for these vari¬ 
ous uses is enormous, and the nearness of water transportation 
bespeaks a considerable future for the industry. 

PETROGRAPHY OF SOME PRECAMBRIC ROCKSi 

It is proposed here to treat, in somewhat more detail than seemed 
suitable in the general account, of certain of the Precambric rocks 
with discussion of chemical analyses. While some of the igneous 
rocks of northern New York have already received detailed study, 
more especially the syenites and certain gabbros, others have been 
comparatively neglected, notably the granites. For the purpose of 


1 By H. P. Cushing. 



176 


NEW YORK STATE MUSEUM 


somewhat atoning for this neglect, analyses have been prepared of 
four samples of granites of the region, as shown in the following 
table: 



1 

2 

3 

4 

5 

6 

Si0 2 . 

76.56 

76.41 

73-33 

73.10 

7 ° • I 3 

66.59 

A1203. 

12.95 

12.41 

13-55 

14.29 

15-47 

14-54 

Fe 2 C >3 . 

. 16 

1.01 

•58 

1.04 

1.52 

2.42 

FeO. 

•37 

•50 

i -53 

1.04 

1.05 

2 -43 

MgO. 

.24 

.46 

•45 

•53 

.85 

1 .18 

CaO. 

1.30 

.78 

1.66 

1.18 

1.60 

2.15 

Na20. 

3-90 

3-34 

5.01 

3.08 

3 - 7 2 

3.08 

K 2 0 . 

4-23 

4-33 

3 • 12 

5-36 

4-39 

5.62 

I1 2 0 +. 

• 2 5 

•34 

\ 45 

/ -54 

. 48 

.46 

LL(J—. 


. 1 3 

/ -45 

• 07 

. 01 


Tib 2 . 

.06 

* O 

•03 

J 

•17 

v. / 

• l8 

• 3 ° 

.81 

Zr 0 2 . 


. 02 





P2O5. 




. O T. 


. 40 

Cl. 

.04 



O 

• °3 

•05 

•°3 




F. 

. 0 3 

. O I 


. 02 

. 00 

. 06 

S. 

’ O 

. 02 

. O I 


. 02 

. 0 7 

. 08 

MnO. 

.02 

.06 

.04 

.07 

/ 

.08 

•23 

BaO. 

. 02 




•05 

•!7 






' 

100.15 

99.84 

99.89 

100.58 

99.86 

100.25 


Note. O2O3 and CO2 absent in nos. 1, 4, 5 and 6. 


1 White (bleached) granite near limestone, 1 mile north of Redwood 
(5K10, Alexandria sheet), from a small boss of Laurentian granite gneiss. 
Analysis by E. W. Morley. 

2 Morris granite of Long Lake quadrangle, one of the later granites of 
the region. N. Y. State Mus. Bui. 115, p. 511. 

3 Laurentian granite gneiss from the Methuen bathylith of central On¬ 
tario. F. D. Adams, Jour. Geol. 17:17. 

4 Laurentian granite gneiss of the Alexandria bathylith, p* mile south 
of Alexandria Bay (6E5, Alexandria sheet), analysis by E. W. Morley. 

5 Laurentian granite gneiss of Antwerp bathylith, 2 miles east of Theresa 
(16M4I:), Theresa sheet), chosen for analysis because of apparent slight 
digestion of amphibolite. E. W. Morley, analyst. 

6 Picton granite, from a quarry 1 mile southeast of Grindstone, Grind¬ 
stone island (2F3, Grindstone sheet). Analysis by E. W. Morley. 

That the granite gneisses hold abundant amphibolite inclusions in 
various stages of digestion, so that the rock is quite variable in 
composition, has already been stated. The rock of analysis 4 was 
carefully selected as representative of the normal, acid phase of 
the rock, free from amphibolite contamination. It is a quite normal, 
rather acid granite, and comparison with analysis 3 shows close 
agreement except that the relative proportions of the alkalies are 

































































GEOLOGY OF THOUSAND ISLANDS REGION 


I 77 


reversed in the two. Calculation of its norm gives the following 
result: 


Or .... 
Ab .... 

31.69' 
26.20 


Class 1, persalane 

An .... 
Co .... 

5.00 

1.50 

* 95-29 

Order 4, britannare 

Qz .... 

3°.4oJ 


Rang 2, toscanase 

Ily .... 
11 & Mt .... 

2.46 1 

i.g 8 j 4 ' 44 

Subrang 3, toscanose 


I he rock of analysis 5 was not the normal acid granite gneiss of 
the locality where it was collected, but somewhat darker colored, 
more basic in appearance, and the field relations definitely suggested 
that it had soaked up some amphibolite. Nevertheless the analysis 
shows that this contamination is in slight amount, and the rock is 
to be classified in the same group as its predecessor, as its calcu¬ 
lated norm shows. 


Or .... 

26.13*i 

Ab .... 

31-44 

An .... 

7-54 

Co .... 

1.83 

Qz .... 

26.94. 

Hy .... 

2 - 5 °] 

11 & Mt .... 

2.70 - 

Py. 

0.2^ 


Class 1, persalane 
Order 4, britannare 
Rang 2, toscanase 

Subrang 3, toscanose 


The mode of these rocks differs so little from the norm that it is 
not thought worth while to present the calculation. Both rocks con¬ 
sist chiefly of feldspars and quartz, with biotite as the principal 
additional mineral, a little magnetite, and trifling amounts of apatite, 
zircon, titanite, muscovite and pyrite. These minerals taken to¬ 
gether only amount to about 6 $ in the first case and 8 $ in the second. 
In each case the surplus of alumina in the norm, calculated as 
corundum, is in just the proper amount to combine with the 
magnesia to form biotite. 


Bleached granite 

The rock of analysis 1 is from the margin of a small granite 
boss-cutting limestone, north of Redwood, which we regard as being 
of Laurentian age, and is a fresh sample of granite whitened by 
adjacent limestone. It is a somewhat more acid rock than the 
preceding. Unfortunately no samples which seemed satisfactory 













1 7 8 


NEW YORK STATE MUSEUM 


for analytical purposes could be obtained from the adjacent red 
granite of the same boss, and this white granite stands as the only 
border rock of any of the granites which has been analyzed. The 
field relations of all the granite masses indicate that their border 
zones, and the dikes which run out from them, are more acid than 
the general mass of the rock, higher in quartz and with much less 
biotite and magnetite. Now the granite cuts and sends dikes into 
all the Grenville rocks, all of this more acid phase, yet it is only 
in the case of adjacent limestone that the border and the dikes 
become white. In the schists and quartzites they remain red, though 
equally acid with the white. In so far then as the higher silica 
and lower iron of the white granite are concerned, the rock is be¬ 
lieved to be merely an average representative of the general, more 
acid border rock, it being confidently held that much of the red, 
border granite or dike granite would show equivalent acidity, and 
like diminution in iron, and that the color change is in no way con¬ 
cerned in these differences. Though no chemical analyses are avail¬ 
able, study of slides of these acid red granites gives results in close 
accord with the analysis of the white, and many of them show 
almost no biotite and magnetite in the rock, hence they are much 
poorer in iron than the rock of analysis 4, though with feldspar 
equally as red in color. Slight differentiation has taken place in 
the granite, producing more acid borders and dikes, and these 
bleached only by limestone. 

The rock classes as a toscanose, as do the others. Yet it is close 
to the vborder line between orders 3 and 4, as shown by its close 
similarity in composition with the red, Morris granite of analysis. 2, 
which falls in order 3 and is an alaskose. 

There is every reason to believe that the coloring matter of the 
red feldspar is ferric oxid; in fact in some of the thin sections, 
minute, red hematite scales are readily made out with high powers. 
In casting about for some chemical explanation of the bleaching of 
the feldspar, chance put me in communication with Dr W. F. Hil- 
lebrand, who most generously furnished me such data as he had at 
command. He writes as follows : 

.. Many years ago, in Denver, I had occasion to analyze a zeolite 
that was colored red by iron oxid. On ignition the red color 
disappeared entirely and almost pure white resulted. This was 
undoubtedly due to a combination between the iron oxid and the 
silicate material. My impression is that the zeolite was a- cal¬ 
cium-aluminum silicate. Since then I have seen in the Chemical 
News, vol. 84, p. 303, a reference to the decolorizing effect of 
alumina on ferric oxid when the two are ignited together * . . 





GEOLOGY OF THOUSAND ISLANDS REGION 179 

Now on hearing of your problem it occurred to me that such an 
effect might be represented by the bleached dikes in limestone. 
The idea was that, under the influence of the intrusions, the lime¬ 
stone may have become decarbonated to a slight extent, thus 
facilitating action with the ferric oxid of the feldspar. The ex¬ 
planation does not, however, satisfy me, for one might expect 
perhaps that the feldspathic material intruded at the elevated 
temperature would have already acted on its iron oxid, and hence 
not show, color; still it may be that the silicate molecule of the 
feldspar is far more resistant than the zeolite and limestone in 
respect to ferric oxid, which might thus be in independent exist¬ 
ence with the feldspar at high temperatures. 

Dr Warth’s article in the Chemical News deals with the blowpipe 
ignition of mixtures of alumina and ferric oxid in various pro¬ 
portions, in which the color invariably changed from red to white 
when small amounts of iron were used, while a brownish tint was 
obtained when the proportions were larger. Incidentally it was 
also shown that the alumina prevented reduction of the iron to the 
magnetic oxid. 

A sample of finely crushed and sorted red granite was ignited 
by us for three hours over a Bunsen flame in a platinum crucible. 
The portion in close contact with the sides and bottom became 
white, while the bulk of the material, in more central position and 
hence less strongly heated, retained its red color. This we take to 
indicate that, with sufficiently high temperature, even in feldspar, 
the red color will disappear, and that the presence in rocks of 
alkali feldspar colored red by ferric oxid shows that, under the 
conditions of congelation, the temperature was not sufficiently high 
to bring about this color change. We then mixed a small quantity 
of powdered limestone with another charge of the crushed granite, 
and ignited in the same crucible over the same burner for the 
same time. Not only was the feldspar of the entire charge bleached, 
but the bleaching seemed complete at the end of one hour. Finally 
we ignited a third charge, in which a very thin coating of lime¬ 
stone was spread over the top, but not mixed with the granite as 
in the previous case, and here again the bleaching was prompt and 
absolute. It is not intended to. imply that the cause of the bleach¬ 
ing was the same in both cases, but only that, in the presence of 
lime, decoloration took place more readily and at a lower tempera¬ 
ture ; precisely what the field relations had indicated for the granite 
in place. There is also here, it seems to us, a hint at the reason 
why red coloration is a common feature in alkali feldspars, and 
not in lime soda feldspars. 


i8o 


NEW YORK STATE MUSEUM 


The amount of ferric oxid in the red feldspar is undoubtedly 
very trifling, so that, if chemical combination has taken place and 
the lime has entered into the reaction the quantity involved is so 
small that it would be a comparatively insignificant feature in the 
complete rock analysis. It is to be noted that the lime is some¬ 
what higher in analysis i than in 4, but, while it is possible that 
this is owing to lime taken up from the limestone and going into 
combination with the iron of the feldspar, it must be remembered 
that the variation is well within the limits of variation which all 
the bases show in the general granite mass, hence it is absolutely 
unsafe to generalize in regard to it. We may have a combination 
of lime, iron and alumina in a spinellike mineral, though lime does 
not, in general, occur in spinel; or a small amount of anorthite 
may be formed, with the iron replacing alumina. The iron may 
perhaps be reduced, forming an iron aluminate, the iron reduced 
to the ferrous condition, though it would seem as if this would 
likely give a green color to the feldspar. Warth argues that his 
color changes need not mean chemical combination of the two oxids 
but rather a diffusion of one in the other. Hillebrand, however, is 
quite confident that combination takes place. He says, “ It is un¬ 
questionable that both lime and alumina decolorize and combine 
with ferric oxid when they are heated together.” Though this 
chemical question must be left indefinite, it does seem to us cer¬ 
tain that the red color of the feldspar may be made to disappear 
merely by sufficiently high and prolonged heating, that the presence 
of lime facilitates the process, lowering the necessary temperature, 
and that with our feldspars here the temperatures were not suf¬ 
ficiently high to discharge the color, or rather to cause'the feldspars 
to crystallize with the iron combined, rather than as free hematite, 
under the 'conditions prevailing at the: place(atnd time 'of solidification ; 
though they were high enough to cause the combination to take 
place when in the vicinity of limestone and under its influence. 

The only difference in the mineralogy of the two rocks is the 
presence in the white rock of occasional, scattered, small black 
tourmalins, which in general do not appear in the other, though 
they are locally present even there. They would seem attributable 
to the presence of mineralizers in the border phase of the granite, 
and in the dikes they occur in the red granites adjacent to other 
rocks than limestone, such as quartzite for example, and seem to 
have nothing whatever to do with the color change. It seems to 
us that the chemical analysis gives no suggestion whatever as to 
the cause of this change. 


GEOLOGY OF THOUSAND ISLANDS REGION 


181 


Picton granite 

The specimen of Picton granite analyzed was selected as an 
average representative of the rock, and bears out the impression 
gained in the field that as a whole it is less acid than the Lauren- 
tian granites where uncontaminated by Grenville material. It 
seems less quartzose, and always shows considerable hornblende, 
which is relatively scarce in the granite gneiss. The thin section 
shows it to be fairly rich in accessory minerals, titanite and apatite 
especially being frequent and fairly coarse, the former particularly 
so. Some pyrite is present, zircon also, little hematite inclusions 
in the feldspars, and ilmenite or rutile needles in the quartz. A few 
minute tourmalin crystals also occur. The green hornblende is alter¬ 
ing to biotite, and there is additional biotite in the rock as well. For 
the feldspars, microperthite, microcline, microcline-microperthite 
and oligoclase are all present in considerable amount, and all with 
strongly marked characters. A good deal of micropegmatite, some 
of it quite coarse, is also to be seen. Altogether, in its minor 
mineralogy, the rock presents considerable contrast to the granite 
gneiss. 

The norm of the rock is a follows: 


Or. . . . 

33-361 

Ab. .. . 

26.20 

An.... 

8.62 ' 

Qz.... 

20.82 

Hy.... 

4.48' 

Mt.... 

3-48 

11. 

i-S 2 - 

Py. . . . 

0.15 

Ap. .. . 

I .OI J 


-89.00 


10.64 


Class 1, persalane 
Order 4, britannare 
Rang 2, toscanase 

Subrang 3, toscanose 


It thus falls iri the same rock group as the granite gneisses, 
but is much nearer the border of the group than they are. The 
greater variety and abundance of the femic and alfenic minerals, 
hornblende, biotite and titanite, would cause the mode to depart 
somewhat more widely from the norm than in the previous cases, 
the lime to form titanite being deducted from the anorthite, re¬ 
leasing alumina for the biotite and diminishing the quartz per 

centage. 

The dike phases of this granite range more acid than this, but 
with this .exception it is thought that the average of the rock com¬ 
position is well represented by the analysis. The composition is 







NEW YORK STATE MUSEUM 


l 82 


toward the basic end of the granites, hence it is not surprising 
•that slight variations toward further basicity should give rise to 
rock with little quartz, like that south of Clayton along French 
creek. Except for this the petrographic agreement is so close in 
all details that there seems no question as to the identity of the two 
rocks. 

Alexandria syenite 

In the previous description of this syenite it has been stated 
that an augen gneiss adjoins it on the south which was taken by 
us in the field for a gneissoid, border phase of the rock, but that 
Smyth dissents from this view. In the field this border rock ap¬ 
pears much the more basic of the two, but closer examination 
shows the presence of much quartz, and chemical and microscopic 
investigation shows it to be much more acid than the syenite. 
Analyses of each follow, with two analyses of the general Adiron¬ 
dack green syenite, thought to be represented in this district by the 
Theresa syenite, (of which no analyses have been made) for pur¬ 
pose of comparison with them. 



1 

2 

3 

4 

5 

Si 0 2 . 

58 • 99 

59-70 

63-45 

66.50 

66.59 

AL03. 

19.22 

I 9 . 5 2 

18.38 

15.66 

M -54 

Fe2C>3.. 

2.83 

I . 89 

1.09 

i -75 

2.42 

FeO. 

2.83 

4.92 

2.69 

2.21 

2.43 

MgO. 

1.25 

.78 

•35 

1.18 

1.18 

CaO. 

3 - 4 i 

3-36 

3.06 

2.15 • 

2.15 

Na 2 0 . 

4-33 

5-31 

5.06 

3-74 

3.08 

K 2 0. 

5 - 6 4 

4.14 

5 -i 5 

5.02 

5.62 

II2O +. 

•35 

1 C 2 


/ -40 

.46 

H 2 0—. 

. 04 

) ‘ 52 

• 3 ° 

l -05 

• •••••• 

TiOs. 

.01 

• • • • • 

.07 

• 7 i 

.81 

P9O0. 

•59 



•59 

A O 





Cl. 

. IO 



.06 

•°3 



* * * 


F. 

. 40 



O C 


S. 

.08 


• • • • • 

• 

. 18 

.08 

MnO . 

. 14 

•9 

trace 

•°3 

•23 

BaO. 

.09 



•05 

T 1 




• 1 7 


IOO.30 

100.23 

99.60 

100.33 

100.25 


1 Alexandria syenite, 3^ miles north of Redwood (8K2, Alexandria 
sheet). E. W. Morley, analyst. 

2 Tupper syenite (laurvikose), N. Y. State Mus. Bui. 115, p. 514. 

3 Loon Lake syenite (p.ulaskose), N. Y. State Mus. Bui. 115, p. 514. 

4 Augen gneiss associated with Alexandria syenite, 2 miles west of north 
of Redwood (6J2, Alexandria sheet), E. W. Morley, analyst. ' 

5 Picton granite, repeated from previous column' of analyses. 



















































GEOLOGY OF THOUSAND ISLANDS REGION 

Norm of Alexandria syenite, analysis i : 

Class i, persalane 
Order 5, Canadare 
Rang 2, pulaskase 
Subrang 3, pulaskose 


The rock itself contains considerable green horblende and biotite 
which, together with the accessory magnetite, titanite, apatite and 
pyrite, constitute about 15$ of the rock, (elsewhere they run up 
to 25 or 30$, carrying the rock into the dosalane class) meaning 
of course that some of the lime, alumina and potash calculated 
with the salic minerals of the norm are in the hornblende and 
biotite. Microcline, microperthite and oligoclase are all present in 
some quantity, plagioclase being somewhat in excess. Some of the 
microperthite is secondary after oligoclase. The rock has beautiful 
cataclastic structure,-showing much more crushing than the Picton 
granite. Chemically it is seen to be very close to the green syenites 
of similar silica percentage, the chief difference being in the higher 
magnesia and in the relative proportions of ferric and ferrous 
iron and of the alkalies. The higher magnesia expresses itself 
mineralogically in the formation of hornblende and biotite, in¬ 
stead of the pyroxenes of the green syenite. The general rock 
is somewhat more basic, and with a higher percentage of ferro- 
magnesian minerals than the normal green syenite. 

The augen gneiss of analysis 4 is a much more acid rock, a tosca- 
nose, suggesting caution in attempting to account for it as a 
phase of the syenite. The analysis is so close to that of the Picton 
granite of the last column as to be almost grotesque. Quite cer¬ 
tainly it has no relation whatever to the Picton granite, though 
mimicing it so closely chemically. The green syenites of the region 
show wider range of variation than that shown in this case, never¬ 
theless the intrusion here is of such comparatively small size that 
variation in composition to this amount would be quite unusual. 
Hence the analyses rather tend to reinforce Smyth’s conclusion 
that we really have here two separate small intrusions, side by side. 

Mineralogically the augen gneiss consists of quartz, feldspars 
and biotite, with accessory magnetite, titanite and apatite, and 


Or. ... 
Ab.... 
An.... 
Co.... 
Qz.... 

Hy 

Mt_ 

FI .... 
Ap.... 


33 - 36 ) 
36.68 
11.12 
1.85 
4.14 

5.00' 

4.18 

0.78 

i -34 


87-15 


u.30 





184 


NEW YORK STATE MUSEUM 


small amounts of hornblende, muscovite, zircon and pyrite. The 
femic minerals constitute 15$ of the rock analyzed. The feldspar 
is chiefly microcline and' oligoclase, though with some microper- 
thite. Both feldspars occur as augen, with trains of granulated ma¬ 
terial running away from them, between which are foliae of quartz, 
feldspar and biotite. To a considerable extent the quartz and 
biotite seem to have resulted from recrystallization of feldspar. 

The certain Alexandria syenite runs into very gneissoid and mica¬ 
ceous border phases, which lie between its massive core, and the 
augen gneiss beyond. These varieties are much more micaceous, 
and much more quartzose than the massive portion, and in them 
also much biotite and quartz have resulted from feldspar re¬ 
crystallization. They are thus very similar to the augen gneiss. It 
was this apparent gradation from one rock to the other in the field 
which gave us the impression that the whole represented a single 
-intrusion. It is a matter of very minor importance in the local 
geology, and must for the present be left as undetermined. 

Granitized amphibolite and amphibolitized granite (soaked 

rocks) 

Practically all observers who have worked in Laurentian areas, 
have seen and recorded the evidences, which meet one on every hand, 
of the attack of the granite upon the amphibolite inclusions, large 
and small, which occur nearly everywhere, and are often abundant. 
The action consists of an injection of granite into the amphibolite, 
at first along the foliation planes, from which the granite spreads 
out more or less into the adjacent rock, injecting itself between and 
inclosing the grains, but with the distinction between the two ma¬ 
terials still sharp. In later stages this sharpness disappears, the 
two materials seem to merge, or fade into one another, and as a 
final stage a rock is produced which seems a true mixed rock, in 
which a distinction between the two elements is no longer possible, 
and whose origin would be problematic except for the occurrence 
of the less advanced phases of the change. Needless to say the 
granite must be very thoroughly molten in order to produce these 
mixed rocks. It was our purpose to investigate these rocks some¬ 
what thoroughly chemically. Unfortunately however no material 
which seemed to us sufficiently fresh to warrant chemical investi¬ 
gation was obtained from rocks which seemed distinctly interme¬ 
diate. A beginning was made, however, by the investigation of two 
rocks, one a granite slightly tinctured with amphibolite, and the 


GEOLOGY OF THOUSAND ISLANDS REGION 



other an amphibolite slightly soaked by granite, and their analyses 
appear herewith. Each, in the field, was classified as plainly a 
soaked rock, in which the constituents were merged. Each was 
also merely a phase in a gradual increase in amount of soaking, 
plainly to be traced in the field, and the two samples were chosen 
from among many because of unusual freshness. 



1 

2 

3 

4 

5 

Si O2. 

73.1° 

70.13 

56.58 

51.42 

50-83 

AI2O3. 

14.29 

15-47 

15-54 

17.42 

18.64 

Fe 203 . 

1.04 

1.52 

3.80 

3- 6 4 

2.84 

FeO. 

1.04 

1.05 

5 - 4 i 

5-!4 

5-97 

MgO. 

•53 

.85 

2.77 

5 • 11 

4.90 

CaO. 

1.18 

1.60 

4.56 

6.76 

7 - 5 o 

Na20. 

3.08 

3 • 72 

2.91 

3-74 

4.22 

K ,0 . 

5-36 

4-39 

4-25 

3-33 

1.83 

h 2 o +. 

•54 

.48 

. 80 

•74 

> 1.40 

H 2 0 —. 

.07 

.01 

. 10 

.09 

J 4 

Ti 0 2 . 

.18 

•30 

1 .71 

1.25 

1.10 

ZrO. 



.01 

.01 


P9CL 

. 0 7 


.87 

• 7 1 


- L J V - / D. 

Cl.•. 

* 0 
•03 

•05 

. 12 

• J 3 

•03 

F . 

. 02 

. og 

. 14 

. 10 


S. 

.02 

.07 

.44 

•23 

.01 

MnO. 

.07 

.08 

.09 

. 16 

. 10 

BaO. 


•05 

.08 

•13 

. 11 CO2 

- 

100.58 

99.86 

100.18 

100.11 

99.48 


Note. O2O3 and CO2 absent. 


1 Laurentian granite gneiss of Alexandria bathylith, from column 4 of 

original table. , , . , 

2 Laurentian granite gneiss of Antwerp bathylith, slightly soaked with 

amphibolite, column 5 of original table. # 

3 Amphibolite, somewhat soaked by granite, from railroad cut 4 miles 
north of Redwood (8L2a, Alexandria sheet). E. W. Morl-ey, analyst 

4 Amphibolite, from same railroad cut (8L2B, Alexandria sheet). 

E. W. Morley, analyst. . , 

5 Amphibolite described by Adams as representing the extreme stage in 

the alteration of crystalline limestone into amphibolite by contact action of 
the Glamorgan bathylith, Jour. Geo. 17:2. 


It is not thought that the amphibolite of analysis 4 is an altered 
limestone, but rather a member of the schist series, though likely a 
calcareous shale, even perhaps an impure limestone. In any case 
its similarity in composition with the amphibolite described by 
Adams from Maxwells Crossing is quite striking, the somewhat 
higher magnesia and potash being the most prominent dififerences. 





















































NEW YORK STATE MUSEUM 


186 

Adams also shows, in his valuable paper, the similarity in compo¬ 
sition of his contact amphibolite with other amphibolites, even some 
of igneous origin. It would seem therefore that we are reasonably 
safe in assuming that analysis 4 will not depart widely in composi¬ 
tion from most of the amphibolites of the region, no matter what 
their origin. 

The analyses of the two granites have been already discussed. 
No. 2 does not depart widely from no. 1 in composition, and might 
well represent a simple variant of the magma. Its field relations, 
however, preclude that supposition and it is to be noted that, when 
compared with analyses 1 and 4, it represents an intermediate stage 
in every single important constituent. On the basis of the silica 
percentage a mixture of six parts of analysis 1 and one part of 
analysis 4 would almost give a rock of the composition of analysis 2. 
Calculated on that basis the following result is arrived at: 



1 

2 

3 

4 

SiC>2. 

70.13 

70.05 

56 • 58 

56.62 

AI2O3. %. 

15-47 

14-73 

15-54 

16.66 

Fe2C>3. 

1.52 

1.42 

3.80 

3 - OI 

FeO. 

1.05 

1.63 

5 - 4 i 

4.14 

MgO. 

.85 

1.18 

2.77 

3-97 

CaO. 

1.60 

1.99 

4-56 

5-53 

Na^O. 

3-72 

3 -i 7 

2.91 

3-58 

K2O. 

4-39 

5.08 

4-25 

3-79 


In column 1 are given the percentages of the soaked rock shown 
by analysis, and in 2 the calculated percentages on the basis stated 
above. They seem to us to be sufficiently alike in every constituent 
to afford a strong probability that the field relations were correctly 
interpreted, and that the rock is a true soaked rock. The greatest 
variation between the two is in the alkali percentages, and these 
are just the ones which vary most in the general granite masses. 
The total amount of alkalies, however, is much the same in each, 
8.11$ in the first case and 8.25$ in the second. 

The granitized amphibolite is not so definitely a soaked rock as 
the other, since the amount of granite in it is so small, that it is 
an impregnated, rather than a mixed rock. Nevertheless the granite 
is thoroughly disseminated through it, though granitizing it in 
patches rather than uniformly. Column 3 gives the rock percent- 
























GEOLOGY OF THOUSAND ISLANDS REGION 


187 


ages of this amphibolite, and column 4 a calculated mixture of 
granite and amphibolite in the ratio of 24$ of the former and y 6 fo 
of the latter. The agreement in this case is not so close as in the 
former one, but in large part the differences can be ascribed to the 
fact that the granite here is not normal, but of the pegmatitic type, 
higher in mineralizers and in iron, and poorer in alumina, lime and 
magnesia than the normal rock. Comparison of analyses 3 and 4 
seems definitely to suggest this, the iron being higher in the grani- 
tized rock than in the amphibolite, and the lime and magnesia much 
lower. It is thought that if an analysis of the neighboring granite 
was available for use in the computation, the agreement would be 
much closer. But the result is somewhat disappointing, and the 
importance to be assigned to the discrepancies a debatable matter, 
likely to vary with the personal equation of the reader. Consider¬ 
ing all the circumstances the agreement seems to us as close* as 
could be hoped for, and indicative of the correctness of interpreta¬ 
tion of the field evidence, namely, that these are true mixed rocks. 



INDEX 


© 


Actinolite, 48, 49, 50. 

Adams, F. D., cited, 25, 31, 33, 51, 
185, 186. 

Adams, 98, 99. 

Alexandria, green schists in, 47-50; 
tourmalin contact zones in, 50-51. 

Alexandria bathylith, 36, 51. 

Alexandria Bay, 27, 155/158, 160, 173. 

Alexandria quadrangle, 5, 6, 62. 

Alexandria syenite, 10-n, 12, 39-40; 
foliation, 102-3; analyses, 182-84. 

Altitudes, in mapped area, 7; Pale¬ 
ozoic, 122. 

Ami, H. M., field work, 6; acknowl¬ 
edgments to, 6; mentioned, 61, 67, 
86 . 

Amphibolites, 31, 33~34, 37, 43, 47, 48, 
50, 173, 176; contact, 51-52; grani- 
tized, 184-87. 

Amphibolitized granite, 184. 

Amsterdam limestone, 97. 

Analyses of some Precambric rocks, 
175 - 87 . 

Andesine, 40, 49. 

Anorthite, 181. 

Anorthosites, 24, 39. 

Anticline, defined, 113. 

Antwerp bathylith, 36, 46; contact 
rocks, 52-53. 

Apatite, 36, 38, 40, 44, 49, 177, 181, 
183. 

Aplite, 36. 

Area of district, 6. 

Augen gneiss, 10, 12, 39, 40, 42; 
analyses, 182, 183. 

Augite, 38, 39, 44, 45- 

Baldwinsville, 123. 

Barite, 173. 

Bathylith, defined, 10. 

Bathyurus extans, 72, 81, 82 84. 

Beemkantown formation, 16, 92, 93, 

94, 97- 


Biotite, 33, 35, 36, 38, 39, 40, 4E 1*9, 
177, 178, 181, 183, 184. 

Birdseye limestone, 79, 80. 

Black creek valley, 113. 

Black river, 7, 81, 126, 128, 133, 135, 
154; glacial diversion, 141-45. 

Black River group, 79, 85. 

Black River limestones, 6, 18, 54, 84, 
85, 96 , 97, 113, 133; quarries, 173 , 

174, 175. 

Black River village, 136. 

Boulder kames, 153. 

Boulder moraines, 152 - 53 . 

Brainerd, cited, 68. 

Branner, J. C., acknowledgments to, 
117; mentioned, 118. 

Brownville, 82, 113, 133, 136. 

Browns Corners, 127, 173. 

Butterfield lake, 26, 113, 127, 132. 

Calcite, 29, 30, 35, 49, 50, 51, 52, 53, 
64. 

Camarotoechia plena, 84. 

Cape Vincent, 156. 

Cape Vincent quadrangle, 5, 121. 
Carleton island, 121. 

Carney, Frank, cited, 166. 

Chadwick, George H., cited, 139. 
Chamberlin, cited, 163. 

Champlain valley, Palezoic Oscilla¬ 
tions of level, 97. 

Chatter marks and gouges, 161-64. 
Chaumont, 87, 90, 121, 160. 

Chaumont bay, 89. 

Chaumont river, 113, 133 , H7, *5°. 
Chazy limestones, 17, 79, 94, 97- 
Chemical analyses of some Precam¬ 
bric rocks, 175 — 87 . 

Chippewa Bay, 160. 

Clay plains, 156-59. 

Clays, pitted, 158. 

Clayton, 42, 72, 151, 153 , 155, ^6 160, 

175 . 

Clayton quadrangle, 5, 121. 





190 


NEW YORK STATE MUSEUM 


Clear lake, 113, 127. 

Climactichnites, 63. 

Climate, changes of, 23, 122. 

Columnaria alveolata, 84. 
halli, 84. 

Conglomerates, 61. 

Consequent streams, 124. 

Contact amphibolites, 51-52. 

Contact rocks, 45-46, 47; of Antwerp, 
bathylith, 52-53. 

Covey Hill gulf, 138. 

Cranberry creek valley, 127. 

Crosby, W. O., cited, 156. 

Crown Point limestone, 97. 

Crystal lake, 127, 132. 

Cumberland Head shale, 97. 

Curved scorings, 160-61. 

Cushing, H. P., introduction,' 5-6; 
location and character, 6-8; sum¬ 
mary of geologic history, 8-22; 
Precambric rocks, 24-54; Paleozoic 
rocks, 54-79; summary of Paleozoic 
oscillations of level, 92-99; rock 
structures, 99-121; topography, 
121-36; economic geology, 172-75; 
petrography of some Precambric 
rocks, 175-87; cited, 80, 143, 166; 
mentioned, 86. 

# 

Dalmanella testudinaria, 91. 

Day Point limestone, 97. 

Deposition, plains of, 148. 

Dexter, 136, 166, 167. 

Diabase, 24, 44-45, 54, 174 - 

Dikes, trap rock, 24, 44, 174; granite, 

4 8 - 

Diopside, 29. 

Diorite, 39. 

Dip of the Paleozoic rocks, 98-99. 

Dolgeville, shale, 97. 

Drainage, original, 124-25; Tertiary, 
125-29; underground, 133-36. 

Eaton, H. N., voluntary assistant, 6; 
acknowledgments to, 6; photo¬ 
graphs by, 57. 

Economic geology, 172-75. 

Ells, R. W., cited, 61, 67, 77. 

Emmons, Ebenezer, cited, 79, 84, 138. 


Endoceras longissimum, 88. 
multitubulatum, 88. 

Epidote, 48, 49, 50. 

Erosion, amount, 123-24; glacial, 
159-64; plains of, 147-48. 

Eskers, 155-56. 

Evans Mills, 113, 154, 160. 

Fairchild, H. L., the Pleistocene, 
23-24; Pleistocene geology, 136-72; 
cited, 6, 98, 115, 126, 138. 

Faults, 118-21. 

Feldspars, 32, 33, 34, 35, 36, 38, 39 , 
40, 41, 44, 45, 46, 48, 49 , 50 , 51, 52 , 
64, 177, 178, 179, 180, 181, 183, 184. 

Felts Mills, 133, 134, 135 , 143, 154 - 

Folds, 108-18; postglacial, 115-18. 

Foliation, 99-103. 

French creek, 113, 114, 150. 

Frontenac axis, 95, 113, 126. 

Gabbros, 24, 44. 

Gananoque, 45. 

Garnet, 33, 34, 35 , 48. 

Geologic history, summary of, 8-22. 

Gilbert, G. K., acknowledgments to, 
117; cited, 117, 138. 

Gilbert gulf, 24, 138-40. 

Glacial deposits, 7, 150-56. See also 
Pleistocene. 

Glacial erosion, 159-64. 

Glacio-aqueous deposits, 156-59. 

Gneisses, 35 , 39, 40 , 42 , 43, 55, 58 . 
See also Faurentian granite gneiss. 

Gneissic granites, 36-38. 

Gonioceras anceps, 84, 87, 88, 90. 

Goose bay, 55. 

Grabau, cited, 67, 78. 

Granites, 24, 30, 36, 48, 49, 50, 55; 
action on amphibolite and quart¬ 
zite, 47; analyses, 176; bleaching by 
limestone, 46; bleached, analyses, 
177-80; gneissic, 36-38; gradation 
into quartzite, 47; quarries, 174; 
red, 46, 179; white, 46. See also 
Picton granite. 

Granite gneiss, 10, 12, 24, 33, 43, 48, 
58; analyses, 176; foliation of, 
101-2. 

Graphite, 29, 35, 53. 



INDEX TO GEOLOGY OF THOUSAND ISLANDS REGION 


191 


Great Bend, 143. 

Grenville limestones, 28, 56, 57, 132; 
resting on an ancient lava flow, 25; 
Potsdam contact on, 58; use for 
road metal, 173. 

Grenville quartzites, 12, 31. 

Grenville rocks, 8, 24, 26-36, 45; of 
Keewatin age, 25; foliation in, 
100-1; folds, 108-9. 

Grenville schists, 12, 34-36, 47, 172; 

Potsdam contact on, 58. 

» 

Grindstone island, granite, 11, 41, 43, 
50, 174; conglomerates, 15; quartz¬ 
ite, 26, 31, 112; dikes, 44; Potsdam 
sandstone, 62; boulder kames, 153. 
Grindstone quadrangle, 5, 6. 

Guffin bay, 89, 115. 

Hall, cited, 79. 

Hammond, 174. 

Helicotoma, 72. 

Hematite, 49, 50, 172, 181. 

Hillebrand, Dr W. F., quoted, 178- 
79, 180. 

Hinds, F. A., cited, 143. 

Hormoceras tenuifilum, 84, 87, 90. 
Hornblende, 33, 34, 35, 38, 39, 40, 41. 

44 , Si. 52, 53 , 1 19 , 181, 183, 184. 
Horse creek, 81. 

Howe Island, 67. 

Hoyt limestone, 97. 

Hyde creek-Perch river valley, 127. 
Hyde lake, 127, 132. 

Hypersthene, 44. 

Igneous rocks, 9-13, 24, 36-38; later 
foliation of, 102-3. 

Illaenus americanus, 90. 

Ilmenite, 181. 

Indian river, 7, 26, 56, 127, 128. 
Inliers, 114. 

Iron ore, 35. See also Hematite. 
Iroquois, Lake, 137-38. 

Iroquois plane, altitude, 139. 

Isle La Motte marble, 79. 

Isochilina, 72. 

Isotelus platycephalus, 90. 


Kames, 153, 154 - 55 - 
Keewatin formation, 25. 

Keuka valley, 166. 

Kingston, 6 , 67, 77; granite, 41. 
Klock’s quarry, 85. 

Knight, cited, 25. 

Labradorite, 44, 49. 

Lafargeville, 151, 153 , 155- 
Lake basins, 148-50. 

Lake Iroquois, 137-38. 

Lakes, 131-33. 

Laurentian granite, 36-38; quarries, 
174- 

Laurentian granite gneiss, 10, 12, 51; 
use for road metal, 173; analyses, 

176 , 185 . 

Leperditia, 72. 

fabulites, 83, 90. 

Leray limestone, 18, 79, 80, 82, 84-90, 
95, 96, 97, 98, 114 , 11 5, 130 , 133, 
134, 135, 136 . 

Leraysville moraine, 160. 

Limerick, 89, 134, 135. 

Limestone flutings, 164. 

Limestone ribbing, 167-69. 
Limestones, 28-31, 55; quarries, 175. 
Lingulepis acuminata, 63, 65, 66. 

Little Falls dolomite, 65, 66, 97. 
Lituites undatus, 84, 88. 

Long Lake gneiss, 38. 

Loon Lake syenite, analysis, 182. 
Lophospira, 72. 
perangulata, 72. 

Lorraine shale, 19, 54, 123, 124. 
Lowville, 77. 

Lowville limestones, 6, 18-20, 54, 79, 
80-84, 85, 89, 95 , 96, 97 , 1 14 , 11 5 , 
130, 132, 133 , 134 , 136; fold, 115, 
116; quarries, 173, 174, 175- 

Magnetite, 33, 36, 38, 40, 44 , 49 , 64, 

177, 178, 183. 

Martinsburg, 70, 77. 

Mather, cited, 79. 

Medina sandstone, 19. 

Medina shale, 123. 

Mica, 29, 32, 36, 40, 50, 52, 64, 119. 
Microcline, 36, 40, 41, 49, 181, 183, 
184. 


Joints, 103-8. 







192 


NEW YORK STATE MUSEUM 


Micropegmatite, 181. 

Microperthite, 32, 35, 36, 38, 40, 41, 
49, 181, 183, 184. 

Miller, W. J., cited, 25, 77, 99. 

Millsite lake, 35, in, 127, 132. 

Mixed rocks, 47. 

Mohawk valley, Paleozoic oscilla¬ 
tions of level, 97. 

Mohawkian series, 79-92. 

Moraines, 151-53. 

Morley, E. W., analyses by, 176. 

Morris granite, 176. 

Mud lake valley, 127. 

Muscovite, 36, 177, 184. 

Natural bridge, 89. 

Old planation surfaces, 170-71. 
Oligoclase, 32, 36, 38, 40, 41, 181, 183, 
184. 

Ontario valley, 126. 

Orleans Four Corners, 115. 

Orthis pervetus, 90. 
tricenaria, 90. 

Orthoceras multicameratum, 81, 82. 
recticameratum, 81, 82. 

Orthoclase, 32, 34, 50. 

Orton, cited, 98. 

Oswego sandstone, 19, 123. 

Outliers, 114. 

Pachydictya acuta, 91. 

Paleozoic altitude and climate, 122- 

23- 

Paleozoic folding, 112-15. 

Paleozoic oscillations of level, sum¬ 
mary of, 92-97. 

Paleozoic rocks, 14-22, 54-92; dip of, 
98-99; faults, 120; joints, 107-8. 

Pamelia limestones, 6, 17-18, 22, 54, 
68-79, 95, 97, 130, 132; age of, 78; 
extent, 77-78; faults, 120; fold, 

115; quarries, 173, 175- 

Pegmatite, 36, 48, 49, 50. 

Perch lake, 64, 71, 132, 150. 

Perch river, 89, 134. 

Petrography of some Precambric 
rocks, 175-87. 

Philomel creek, 133. 

Phlogopite, 29, 32, 35, 53. 

Physiography, 141-50. 


Phytopsis, 75, 80. 
tubulosum, 83. 

Picton granite, Ji-13, 39 , 4 ^, 4 1 , 4§, 
50, 51, 103, 119; analyses, 176, 181- 
82; quarries, 174. 

Pitted clays, 158. 

Plagioclase, 34, 40, 49, 183. 

Plateaus, 129-31. 

Plectambonites sericeus, 91, 92. 

Pleistocene, 23-24, 136-72. 

Plessis, 127, 147. 

Pleurotomaria hunterensis, 65. 

Postglacial folds, 115-18. 

Potsdam sandstone, 14-15, 48, 54, 60- 
63, 92 , 97 , 98 , 114, 123, 129, 159 , 161, 
170; age • of, 66-68; faults, 120; 
fold, 115; inliers of Precambric 
rocks, 55; Precambric surface 
underneath, 54-60; quarries, 173; 
use as road rock, 173; used for ' 
building and flagging purposes, 174. 

Prasopora simulatrix, 91. 

Precambric erosion, 53-54. 

Precambric rocks, 24-54; faults, 118; 
folding, 109-12; joints, 104-6; 
petrography of, 175-87. 

Precambric surface underneath the 
Potsdam, 54-60. 

Prewisconsin glaciation, 164-72. 

Prospect Park, 155. 

Pyrite, 32, 35, 44, 49, 53, 64, 177, 181, 
183, 184. 

Pyroxene, 29, 32, 33, 34, 35, 48, 49, 

50 , 51, 52 , 53 , 1 19 - 

Pyroxenic limestone, 29. 

Quarry industry, 173-75. 

Quartz, 29, 32, 33, 34, 35, 36, 38, 39 , 
40, 41, 48, 49, 57, 61, 64, 177, 178, 
181, 182, 183, 184. 

Quartzite, 30, 31 S3, 37 , 43, 47 , 48; 50, 

51, 55, 57, 59, 61; gradation of 
granite into, 47. 

1 

Rafinesquina incrassata, 83. 
minnesotensis, 83. 

Redwood, 153, 162, 163, 177. 

Redwood lakes, 151. 

Reid, H. F., acknowledgments to, 

117; cited, 118. 




INDEX TO GEOLOGY OF THOUSAND ISLANDS REGION 193 


Ribbed limestone, 167-69. 

Rideau, Ont., 61. 

Road metal, 173-74. 

Roaring creek, 77. 

Robbins island, granite, 11, 41. 

Rock cliffs of region, 22. 

Rock knobs, 146-47. 

Rock structures, 99-121. 

Rocks, 24-92. 

Rossie road, 57. 

Ruedemann, R., Mohawkian series, 
79-92; mapping of quadrangles, 5, 
115, 121 ; cited, 65, 134, 135. 

Rutile, 32, 181. 

St Lawrence county, beeches and 
deltas of Lake Iroquois, 139. 

St Lawrence valley, 126. 

Salisbury, R. D., cited, 156. 

Sandstone quarries, 174-75. 

Sanford Center, 80. 

Sanford Corners, 75, 76, 154, 160. 
Saranac gneiss, 38. 

Saratoga vicinity, Paleozoic oscilla¬ 
tions of level, 97. 

Saratogan, 97. 

Scapolite, 51, 53. 

Scarps, 129-31. 

Schists, 30, 31, 34-36, 37, 50, 55, 57; 

green, in Alexandria, 47-50. 

Seely, cited, 68. 

Serpentine, 29. 

Seven foot tier, 79, 84, 85, 86, 87, 89, 
90, 92. 

Sillimanite, 35. 

Sixberry lake, 127, 132. 

Smyth, C. H. jr, mapped major por¬ 
tion of Wellesley island, 5; report 
on Alexandria and Grindstone 
sheets, 6; cited, 27, 31, 36, 40, 45, 
50, 5L 54, 57, 62, 119, 182, 183. 
Stock, defined, 10. 

Stone Mills, 71. 

Stone quarries, 173. 

Stones River limestone, 17-18, 78, 95 - 
Striations, 159-60. 

Stromatocerium, 80. 

Strophomena filitexta, 90. 

Strough, 155. 

Subsequent streams, 124. 


Syenites, 24, 39, 44; analyses, 182-84; 
southwest of Theresa, n. See also 
Alexandria syenite; Theresa syen¬ 
ite. 

Syncline, defined, 113. 

Talc, 53. 

Taylor, F. B., cited, 166. 

Terraces, 129-31. 

Tertiary drainage, 125-29. 

Tertiary uplift, 125. 

Tetradium cellulosum, 80, 81, 82, 83, 
84, 90. 

syringoporoides, 72, 84. 

Theresa, 52, 57, 58, 59, 98, 113, 128, 
155, 160, 173. 

Theresa formation, 15-16, 54, 60, 64- 
68, 92, 97 , 98 , 114, 1 15 , 130, 133 , 147 ; 
age of, 65 - 68 ; composed of two 
unconformable formations, 16; in 
part of Ozarkic and in part of 
Tribes Hill age, 65; term to be 
restricted, 66; uplift following, 16-. 

Theresa Junction, 155. 

Theresa quadrangle, 7; mapping, 5; 
Potsdam sandstone, 60, 62. 

Theresa syenite, 38, 182; foliation, 
102-3. 

Threemile Bay, 89, 91, 92, 114, 115. 

Till, 151; old, 166. 

Titanite, 32, 35 , 36, 38. 40, 49, 52, 64, 
1 77 , 181, 183. 

Topography, 121-36, 145-50. 

Tourmalin, 46, 48, 49, 50, 181 ; con¬ 
tact zones in Alexandria, 50-51. 

Trap rock dikes, 24, 44, 174. 

Tremolite, 53. 

Trenton Falls, Paleozoic oscillations 
of level, 97. 

Trenton group, 79, 97. 

Trenton limestone, 18-20, 22, 54, 90- 
92, 96, 97, 98, 121, 123, 130; use for 
road metal, 174. 

Tribes Hill limestone, 16, 64-68, 93, 
97 - 

Tupper syenite, analysis, 182. 

Ulrich, E. O., field work, 6; acknowl¬ 
edgments to, 6; cited, 65, 72, 74, 75, 
76, 78, 79, 82, 85, 93, 95, 136; men¬ 
tioned, 86. 



194 


NEW YORK STATE MUSEUM 


Underground drainage, 133-36. 

Utica shales, 19, 54, 96, 97, 98, 123, 
124. 

Valcour limestone, 97. 

Valleys of the region, 21. 

Vanuxem, cited, 79. 

Walcott, cited, 67. 

Warth, cited, 179, 180. 

Watertown, 82, 86, 89, 113, 136, 151, 
152 . 

Watertown limestone, 18-20, 79, 84- 
9 °, 96 , 97 , 121, 130, 133. 


Watertown region, oscillations of 
level, 97. 

Weathered surfaces, 169-70. 
Wellesley island, mapping, 5; granite, 
11, 12, 41, 43, 50, 51; conglomerates, 
15; quartzite, 26, 31, 112; dikes, 45; 
Potsdam sandstone, 60,. 62. 

West creek, 128, 154. 

Wilson, A. W. G., cited, 59, 126, 128, 

131, 141. 

Wisconsin ice sheet, weak erosion, 
171-72. 

Woodworth, J. B., cited, 63, 138. 
Zircon, 32, 36, 38, 49, 64, 177, 181, 184 



New York State Education Department 

New York State Museum 


John M. Clarke, Director 

PUBLICATIONS 

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M 

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NEW YORK STATE EDUCATION DEPARTMENT 


Descriptions and illustrations of edible, poisonous and unwholesome fungi of New York 
have also been published in volumes i and 3 of the 48th (1894) museum report and in volume 
1 of the 49th (1895), 51st (1897), 52d (1898), 54th (1900), 55th (1901), in volume 4 of the 
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Bulletins are grouped in the list on the following pages according to divisions. 


The divisions to which 

1 Zoology 

2 Botany 

3 Economic Geology 

4 Mineralogy 

5 Entomology 

6 

7 Economic Geology 

8 Botany 

9 Zoology 

10 Economic Geology 

11 “ 

12 “ 

13 Entomology 

14 Geology 

15 Economic Geology 
u6 Archeology 

17 Economic Geology 

18 Archeology 

19 Geology 

20 Entomology 

21 Geology 

22 Archeology 

23 Entomology 

24 

25 Botany 

26 Entomology 

27 “ 

28 Botany 

29 Zoology 

30 Economic Geology 

31 Entomology 

32 Archeology 

33 Zoology 

34 Paleontology 

35 Economic Geology 

36 Entomology 
3 7 

38 Zoology 

39 Paleontology 

40 Zoology 

41 Archeology 

42 Paleontology 

43 Zoology 

44 Economic Geology 

45 Paleontology 

46 Entomology 

47 “ 

48 Geology 

49 Paleontology 


bulletins belong are as follows: 

50 Archeology 

51 Zoology 

52 Paleontology 

53 Entomology 

54 Botany 

55 Archeology 

56 Geology 

57 Entomology 

58 Mineralogy 

59 Entomology 

60 Zoology 

61 Economic Geology 

62 Miscellaneous 

63 Paleontology 

64 Entomology 

65 Paleontology 

66 Miscellaneous 

67 Botany 

68 Entomology 

69 Paleontology 

70 Mineralogy 

71 Zoology 

72 Entomology 

73 Archeology 

74 Entomology 

75 Botany 

76 Entomology 

77 Geology 

78 Archeology 

79 Entomology 

80 Paleontology 

81 

82 

83 Geology 

84 

85 Economic Geology 

86 Entomology 

87 Archeology 

88 Zoology 

89 Archeology 

90 Paleontology 

91 Zoology 

92 Paleontology 

93 Economic Geology 

94 Botany 

95 Geology 

96 

97 Entomology 


98 Mineralogy 

99 Paleontology 

100 Economic Geology 
1 o 1 Paleontology 

102 Economic Geology 

103 Entomology 

_ . U 

I 04 

105 Botany 

106 Geology 

T _ _ U 

107 

108 Archeology 

109 Entomologv 
no 

in Geology 

112 Economic Geology 

113 Archeology 

114 Paleontology 

115 Geology 

116 Botany 

117 Archeology 

118 Paleontology 

119 Economic Geology 

120 “ 

1 21 Director’s report for 1907 

122 Botany 

123 Economic Geology ] 

124 Entomology 

125 Archeology 

126 Geology 

127 “ 

128 Paleontology 

129 Entomology 

130 Zoology 

131 Botany 

132 Economic Geology 

133 Director’s report for 1908 

134 Entomology 

135 Geology 

136 Entomology 

137 Geology 

138 

139 Botany 

140 Director’s report for 1909 

141 Entomology 

142 Economic geology 

143 “ 

144 Archeology 

145 Geology 


fek Bulletins are also found with the annual reports of the museum as follows: 


Bulletin Report 

Bulletin 

Report 

Bulletin 

Report 

Bulletin 

Report 

12-15 

48, V. 

1 

69 

56, v. 2 

97 

58, v. 5 

125 

62, v. 3 

16,17 

50, v. 

1 

70,71 

57, v. 1, pt 1 

98,99 

59, v. 2 

126-28 

62, V. I 

18,19 

5 i. v. 

1 

72 

57, v. 1, pt 2 

100 

59, v. 1 

1 29 

62, V. 2 

20-25 

52, V. 

1 

73 

57, v. 2 

IOI 

59. v. 2 

130 

62, v. 3 

26-31 

53 . V. 

1 

74 

57, v. 1, pt 2 

102 

59 , v. 1 

131,132 

62, v. 2 

32-34 

54 . v. 

1 

75 

57, v. 2 

103-5 

59. v. 2 

i 33 

62, V. I 

35.36 

54 . v. 

2 

76 

57, v. 1, pt. 2 

106 

59 , v. 1 

i 34 

62, V. 2 

3 7-44 

54 . v. 

3 

77 

57, v. 1, pt. 1 

107 

60, v. 2 



45-48 

54 . v. 

4 

78 

57. v. 2 

108 

60, v. 3 



49-54 

55. v. 

1 

79 

57, v. 1, pt 2 

109,110 

60, v. 1 



55 

56, v. 

4 

80 

57, v. 1, pt 1 

in 

60, v. 2 



56 

56 , v. 

1 

81,82 

58 , v. 3 

112 

60, v. 1 

Memoir 


57 

56 , V. 

3 

83.84 

58, v. 1 

113 

60, v. 3 

2 

49 , V. 3 

58 

56, V. 

1 

85 

58, V. 2 

114 

.60, V. I 

3,4 

53 , v. 2 

59 . 6 o 

56 , v. 

3 

80 

58 , v. 5 

115 

60, v. 2 

5,6 

5 7 , v. 3 

5 i 

56 , V. 

1 

87-89 

58, v. 4 

116 

60, v. 1 

/ 

5 7 , v. 4 

62 

56 , v. 

4 

90 

58 , v. 3 

117 

60, V. 3 

8, pt 1 

59 , v. 3 

63 

56 , v. 

2 

9 i 

58, v. 4 

118 

60, v. 1 

8, pt 2 

59 , v. 4 

64 

56 , v. 

3 

92 

58, v. 3 

119-21 

61, v. 1 

9 , Pt 1 

60, v. 4 

65 

56 , v. 

2 

93 

58, v. 2 

122 

61, v. 2 

9 , Pt 2 

62, v. 4 

66,67 

56, v. 

4 

94 

58, v. 4 

123 

61, V. I 

10 

60, v. 5 

68 

56, v. 

3 

95,96 

58, v. 1 

1 24 

61, V. 2 

11 

61, v. 3 


MUSEUM PUBLICATIONS 


The figures at the beginning of each entry in the following list indicate its number as a 
museum bulletin. 

Geology. 14 Kemp, J. F. Geology of Moriah- and Westport Townships, 
Essex Co. N. Y., with notes on the iron mines. 38p. il. 7pl. 2 maps. 
Sept. 1895. Free. 

19 Merrill, F. J. H. Guide to the Study of the Geological Collections of 
the New York State Museum. 164P. ngpl. map. Nov. 1898. Out of print . 
21 Kemp, J. F. Geology of the Lake Placid Region. 24p. ipl. map. Sept. 
1898. Free. 

48 Woodworth, J. B. Pleistocene Geology of Nassau County and Borough 
of Queens. 58p. il. 8pl. map. Dec. 1901. 25c. 

56 Merrill, F. J. H. Description of the State Geologic Map of 1901. 42p. 

2 maps, tab. Nov. 1902. Free. 

77 Cushing, H. P. Geology of the Vicinity of Little Falls, Herkimer Co. 
98p. il. i5pl. 2 maps. Jan. 1905. 30c. 

83 Woodworth, J. B. Pleistocene Geology of the Mooers Quadrangle. 62p. 

25pl. map. June 1905. 25c. 

84 — — Ancient Water Levels of the Champlain and Hudson Valleys. 2o6p. 

il. npl. 18 maps. July 1905. 45c. 

95 Cushing, H. P. Geology of the Northern Adirondack Region. i88p. 

1 spl. 3 maps. Sept. 1905. 30c. 

96 Ogilvie, I. H. Geology of the Paradox Lake Quadrangle. 54p. il. i7pl. 

map. Dec. 1905. 30c. 

106 Fairchild, H. L. Glacial Waters in the Erie Basin. 88p. i4pl. 9 maps. 
Feb. 1907. Out of print. 

107 Woodworth, J. B.; Hartnagel, C. A.; Whitlock, H. P.; Hudson, G. H.; 

Clarke, J. M.; White, David & Berkev, C. P. Geological Papers. 388p. 
54pl. map. May 1907. 90c, cloth. 

Contents: Woodworth, J. B. Postglacial Faults of Eastern New York. 

Hartnagel, C. A. Stratographic Relations of the Oneida Conglomerate. 

-Upper Siluric and Lower Devonic Formations of the Skunnemunk Mountain Region. 

Whitlock, H. P. Minerals from Lyon Mountain, Clinton Co. 

Hudson, G. H. On Some Pelmatozoa from the Chazy Limestone of New York. 

Clarke, J. M. Some New Devonic Fossils. 

- An Interesting Style of Sand-filled Vein. 

- Eurypterus Shales of the Shawangunk Mountains in Eastern New York. 

White, David. A Remarkable Fossil Tree Trunk from the Middle Devonic of New York. 
Berkey, C. P. Structural and Stratigraphic Features of the Basal Gneisses of the High¬ 
lands. 

hi Fairchild, H. L. Drumlins of New York. 6op. 2 8pl. 19 maps. July 
1907. Out of print. 

115 Cushing, H. P. Geology of the Long Lake Quadrangle. 88p. 2opl. 
map. Sept. 1907. Out of print. 

126 Miller, W. J. Geology of the Remsen Quadrangle. 54p. il. npl. map. 

Jan. 1909. 25c. 

127 Fairchild, H. L. Glacial Waters in Central New York. 64P. 2 7pl. 15 
maps. Mar. 1909. 40c. 

135 Miller, W. J. Geology of the Port Leyden Quadrangle, Lewis County, 
N. Y. 62p. il. 1 ipl. map. Jan. 1910. 25c. 

137 Luther, D. D. Geology of the Auburn-Genoa Quadrangles. 36p. map. 

Mar. 1910. 20O 

138 Kemp, J. F. & Ruedemann, Rudolf. Geology of the Elizabethtown 

and Port Henry Quadrangles. i76p. il. 2opl. 3 maps. Apr. 1910. 40c. 

145 Cushing, H. P.; Fairchild, H. L.; Ruedemann, Rudolf & Smyth, C. H. 
Geology of the Thousand Island Region. ig4P- iL 62pl. 6 maps. Dec. 
1910. 75c. 

Berkey, C. P. Geologic Features and Problems of the Catskill Aqueduct. 
In press. 

Gordon, C. E. Geology of the Poughkeepise Quadrangle. In press. 
Luther, D. D. Geology of the Honeoye-Wayland Quadrangles. In press. 
Economic geology. 3 Smock, J. C. Building Stone in the State of New 
York. 1540. Mar. 1888. Out of print. 

7 - First Report on the Iron Mines and Iron Ore Districts in the State 

of New York. 78p. map. June 1889. Out of print. 

10 - Building Stone in New York. 2iop. map, tab. Sept. 1890. 40c. 

11 Merrill, F. J. H. Salt and Gypsum Industries of New York. 94p. i2pl. 

2 maps, 11 tab. Apr. 1893. [50c] 

12 Ries, Heinrich. Clay Industries of New York. 174p. ipl. il. map. Mar. 

1895. 30c. j 








NEW YORK STATE EDUCATION DEPARTMENT 


i5%Merrill, * F. J. H. Mineral Resources of New York. 240P. 2 maps 
Sept A1895. [50c.] 

17 - Road Materials and Road Building in New Tork. 5 2 P- J 4 pk 2 

maps. Oct. 1897. 15c. 

30 Orton, Edward. Petroleum and Natural Gas in New ^ ork. 136P. il. 

■ 3 maps. Nov. 1899. 15c. 

35 Ries, Heinrich. Clays of New York; their Properties and Uses. 45 6p. 
i4opl. map. June 1900. Out of print. 

44 - Lime and Cement Industries of New York; Eckel, E. C. Chapters 

on the Cement Industry. 332P. ioipl. 2 maps. Dec. 1901. 85c, cloth. 

61 Dickinson, H. T. Quarries of Bluestone and other Sandstones in New 
York. 114p. i8pl. 2 maps. Mar. 1903. 35c. 

S5 Rafter, G. W. Hydrology of New York State. 902p. il. 44pl. 5 maps. 
May 1905. $1.50, cloth. 

93 Newland, D. H. Mining and Quarry Industry of New York/ 78p. 
July 1905. 23c. 

100 McCourt, W. E. Fire Tests of Some New York Building Stones. 4°P- 
26pl. Feb. 1906. 15c. 

102 Newland, D. H. Mining and Quarry Industry of New York 1905. 
i62p. June 1906. 25c. 

112 - Mining and Quarry Industry of New York 1906. 82p. July 

1907. Out of print. 

119 - & Kemp, J. F. Geology of the Adirondack Magnetic Iron Ores 

with a Report on the Mineviile-Port Henry Mine Group. 184P. i4pl. 
8 maps. Apr. 1908. 35c. 

120 Newland, D. H. Mining and Quarry Industry of New York 1907. 82p. 

July 1908. Out of print. 

123 —-& Hartnagel, C. A. Iron Ores of the Clinton Formation in New 

York State. 76p. il. i4pl. 3 maps. Nov. 1908. 25c. 

132 Newland, D. H. Mining and Quarry Industry of New York 1908. 98p. 

July 1909. 15c. 

142 -Mining and Quarry Industry of New York for 1909. 98p. August 

1910. 15c. 

143 -Gypsum Deposits of New York. 94p. 2opl. 4 maps. Oct. 1910. 

35 C. 

Mineralogy. 4 Nason, F. L. Some New York Minerals and their Localities. 
22p. ipl. Aug. 1888. Free. 

58 Whitlock, H. P. Guide to the Mineralogic Collections of the New York 
State Museum. i3op. il. 39pl. 11 models. Sept. 1902. 40c. 

70 - New York Mineral Localities, nop. Oct. 1903. 20c. 

98 — Contributions from the Mineralogic Laboratory. 38p. 7pl. Dec. 

1905. Out of print. 

Paleontology. 34 Cumings, E. R. Lower Silurian System of Eastern Mont¬ 
gomery County; Prosser, C. S. Notes on the Stratigraphy of Mohawk 
Valley and Saratoga County, N. Y. 74p. i4pl. map. May 1900. 15c. 

39 Clarke, J. M. Simpson, G. B. & Loomis, F. B. Paleontologic Papers 1. 
72p. il. i6pl. Oct. 1900. 15c. 

Contents: Clarke, J. M. A Remarkable Occurrence of Orthoceras in the Oneonta Beds of 
the Chenango Valley, N. Y. 

- Paropsonema cryptophya; a Peculiar Echinoderm from the Intumescens-zone 

(Portage Beds) of Western New York. 

—-— Dictyonine Hexactinellid Sponges from the Uoper Devonic of New York. 

- The Water Biscuit of Squaw Island, Canandaigua Lake, N. Y. 

Simpson, G. B. Preliminary Descriptions of New Genera of Paleozoic Rugose Corals. 
Loomis, F. B. Siluric Fungi from Western New York. 

42 Ruedemann, Rudolf. Hudson River Beds near Albany and their Taxo¬ 
nomic Equivalents. n6p. 2pl. map. Apr. 1901. 25c. 

45 Grabau, A. W. Geology and Paleontology of Niagara Falls and Vicinity. 

286p. il. i8pl. map. Apr. 1901. 63c; clpth, 90c. 

49 Ruedemann, Rudolf; Clarke, J. M. & Wood, Elvira. Paleontologic 
Papers 2. 240P. i3pl. Dec. 1901. Out of print. 

Contents: Ruedemann, Rudolf. Trenton Conglomerate of Rysedorph Hill. 

Clarke, J. M. Limestones of Central and Western New York Interbedded with Bitumi¬ 
nous Shales of the Marcellus Stage. 

Wood, Elvira. Marcellus Limestones of Lancaster, Erie Co., N. Y. 

Clarke, J. M. New Agelacrinites. 

- Value of Amnigenia as an Indicator of Fresh-water Deposits during the Devonic of 

New York, Ireland and the Rhineland. 














MUSEUM PUBLICATIONS 


52 Clarke, J. M. Report of the State Paleontologist 1901. 28op. il. iopl. 

map, 1 tab. July 1902. 40c. 

63 — & Luther, D. D. Stratigraphy of Canandaigua and Naples Quad¬ 
rangles. 78p. map. June 1904. 25c. 

65 Clarke, J. M. Catalogue of Type Specimens of Paleozoic Fossils in the 
New York State Museum. S48P. May 1903. $1.20, cloth. 

69 Report of the State Paleontologist 1902. 464P. 52pl. 7 maps. Nov. 

1903. $1, cloth. 

80 Report of the State Paleontologist 1903. 396p. 29pl. 2 maps. 

Feb. 1905. 85c, cloth. 

81 - & Luther, D. D. Watkins and Elmira Quadrangles. 32p. map. 

Mar. 1905. 25c. 

82 -Geologic Map of the Tully Quadrangle. 4op. map. Apr. 1905. 20c. 

90 Ruedemann, Rudolf. Cephalopoda of Beekmantown and Chazy For¬ 
mations of Champlain Basin. 224P. il. 38pl. May 1906. 75c, cloth. 

92 Grabau, A. W. Guide to the Geology and Paleontology of the Schoharie 
Region. 314P. il. 26pl. map. Apr. 1906. 75c, cloth. 

99 Luther, D. D. Geology of the Buffalo Quadrangle. 32p. map. May 
1906. 20c. 

101 - Geology of the Penn Yan-Hammondsport Quadrangles. 28p. 

map. July 1906. 25c. 

114 Hartnagel, C. A. Geologic Map of the Rochester and Ontario Beach 
Quadrangles. 36p. map. Aug. 1907. 20c. 

118 Clarke, J. M. & Luther, D. D. Geologic Maps and Descriptions of the 
Portage and Nunda Quadrangles including a map of Letchworth Park. 
5op. i6pl. 4 maps. Jan. 1908. 35c. 

128 Luther, D. D. Geology of the Geneva-Ovid Quadrangles. 44p. map. 
Apr. 1909. 20c. 

•-Geology of the Phelps Quadrangle. In preparation. 

Whitnall, H. O. Geology of the Morrisville Quadrangle. Prepared. 
Hopkins, T. C. Geology of the Syracuse Quadrangle. Prepared. 

Hudson, G. H. Geology of Valcour Island. In preparation. 

Zoology. 1 Marshall, W. B. Preliminary List of New York Unionidae. 
2 op. Mar. 1892. Free. 

9- Beaks of Unionidae Inhabiting the Vicinity of Albany, N. Y. 3op. 

ipl. Aug. 1890. Free. 

29 Miller, G-. S. jr. Preliminary List of New York Mammals. 124P. Oct. 
1899. 15c. 

33 Farr, M. S. Check List of New York Birds. 224P. Apr. 1900. 25c. 

38 Miller, G. S. jr. Key to the Land Mammals of Northeastern North 
America. io6p. Oct. 1900. 15c. 

40 Simpson, G. B. Anatomy and Physiology of Polygyra albolabris and 
Limax maximus and Embryology of Limax maximus. 82p. 2 8pl. Oct. 
1901. 25c. 

43 Kellogg, J. L. Clam and Scallop Industries of New York. 36p. 2pl. 
map. Apr. 1901. Free. 

51 Eckel, E. C. & Paulmier, F. C. Catalogue of Reptiles and Batrachians 
of New York. 64p.il. ipl. Apr. 1902. Out of print. 

Eckel, E. C. Serpents of Northeastern United States. ' 

Paulmier, F. C. Lizards, Tortoises and Batrachians of New York. 

60 Bean, T. H. Catalogue of the Fishes of New York. 784P. Feb. 1903. 
$1, cloth. 

71 Kellogg, J. L. Feeding Habits and Growth of Venus mercenaria. 3op. 
4pl. Sept. 1903. Free. 

88 Letson, Elizabeth J. Check List of the Mollusca of New York. n6p. 
May 1905. 20c. 

91 Paulmier, F. C. Higher Crustacea of New York City. 78p. il. June 

1905. 20c. 

130 Shufeldt, R. W. Osteology of Birds. 382P. il. 26pl. May 1909. 50c. 

Entomology. 5 Lintner, J. A. White Grub of the May Beetle. 34p. il. 
Nov. 1888. Free. 

6 -Cut-worms. 38p. il. Nov. 1888. Free. 

13-San Jos6 Scale and Some Destructive Insects of New York State. 

54p. 7pl. Apr. 1895. 15c. 













NEW YORK STATE EDUCATION DEPARTMENT 


20 Felt, E. P. Elm Leaf Beetle in New York State. 46p. il. 5pl. June 
1898. Free. 

See 57. 

23 - 14th Report of the State Entomologist 1898. i5op. il. ppl. Dec. 

1898. 20c. 

24 -Memorial of the Life and Entomologic Work of J. A. Lintner Ph.D. 

State Entomologist 1874-98; Index to Entomologist’s Reports 1-13. 3i6p. 
ipl. Oct. 1899. 35c. 

Supplement to 14th report of the State Entomologist. 

26 - Collection, Preservation and Distribution of New York Insects. 

36p. il. Apr. 1899. Free. 

27 - Shade Tree Pests in New York State. 2 6p. il. 5pl. May 1899. 

Free. 

31 - 15th Report of the State Entomologist 1899. i28p. June 1900. 

f^c. 

36 - — 16th Report of the State Entomologist 1900. n8p. i6pl. Mar. 

1901. 25c. 

37 -Catalogue of Some of the More Important Injurious and Beneficial 

Insects of New York State. 54p. il. Sept. 1900. Free. 

46 - — Scale Insects of Importance and a List of the Species in New York 

State. 94P. il. i5pl. June 1901. 25c. 

47 Needham, J. G. & Betten, Cornelius. Aquatic Insects in the Adiron- 

dacks. 234P. il. 36pl. Sept. 1901. 45c. 

53 Felt, E. P. 17th Report of the State Entomologist 1901. 23 2p. il. 6pl. 

Aug. 1902. Out of print. 

57 - Elm Leaf Beetle in New York State. 46p. il. 8pl. Aug. 1902. 

Out of print. 

This is a revision of 20 containing the more essential facts observed since that was pre - 
pared. 

59 - Grapevine Root Worm. 4op. 6pl. Dec. 1902. 15c. 

See 72. 

64 - - 18th Report of the State Entomologist 1902. nop. 6pl. May 

1903. 20c. 

68 Needham, J. G. & others. Aquatic Insects in New York. 322p. 52pl. 
Aug. 1903. 80c, cloth. 

72 Felt, E. P. Grapevine Root Worm. 58p. i3pl. Nov. 1903. 20c. 

This is a revision of 59 containing the more essential facts observed since that was pre¬ 
pared. 

74 - & Joutel, L. H. Monograph of the Genus Saparda. 88p. i4pl. 

June 1904. 25c. 

76 Felt, E. P. 19th Report of the State Entomologist 1903. i5op. 4pl. 

1904. 15c. 

79 -- Mosquitos or Culicidae of New York. i64p. il. 57pl. tab. Oct. 

1904. 40c. 

86 Needham, J. G. & others. May Flies and Midges of New York. 352p. 
il. 3 7pl. June 1905. 80c, cloth. 

97 Felt, E. P. 20th Report of the State Entomologist 1904. 246P. il. i9pl. 

Nov. 1905. 40c. 

103 -Gipsy and Brown Tail Moths. 44p. iopl. July 1906. 15c. 

104 —— 21st Report of the State Entomologist 1905. i44p. iopl. Aug. 

1906. 25c. 

109 -Tussock Moth and Elm Leaf Beetle. 34p. 8pl. Mar. 1907. 20c. 

no - 22d Report of the State Entomologist 1906. i52p. 3pl. June 

1907. 25c. 

124 -23d Report of the State Entomologist 1907. 542p. 44pl. il. Oct. 

1908. 75c. 

129 -Control of Household Insects. 48p: il. May 1909. Out of print. 

134 - 24th Report of the State Entomologist 1908. 2o8p. i7pl. il. 

Sept. 1909. 35c. 

136 - — Control of Flies and Other Household Insects. 56p. il. Feb. 

1910. 15c. 

This is a revision of 129 containing the more essential facts observed since that was pre¬ 
oared. 























MUSEUM PUBLICATIONS 


141 Felt, E. P. 25th Report of the State Entomologist 1000. i78p. 22pl. il. 

July 1910. 35c. 

Needham, J. G. Monograph on Stone Flies. In preparation. 

Botany. 2 Peck, C. H. Contributions to the Botany of the State of New 
York. 72P. 2pl. May 1887. Out of print. 

® Boleti of the United States. 9^P- Sept. 1889. Out of print. 

2 5 Report of the State Botanist 1898. 76p. 5pl. Oct. 1899. Out of 


28 
54 - 
97 - 

65 - 

74 - 
105 
116 
122 

131 

139 


print. 


Plants of North Elba. 2o6p. map. June 1899. 20c. 

Report of the State Botanist 1901. 58p. 7pl. Nov. 1902. 40c. 

Report of the State Botanist 1902. 196P. 5pl. May 1903. 50c. 

Report of the State Botanist 1903. 7op. 4pl. 1904. 40c. 

Report of the State Botanist 1904. 6op. iopl. July 1905. 40c. 

Report of the State Botanist 1905. io8p. i2pl. Aug. 1906. 50c. 

Report of the State Botanist 1906. i2op. 6pl. [uly 1907. 35c. 

Report of the State Botanist 1907. i78p. 5pl. Aug. 1908. 40c. 

Report of the State Botanist 1908. 2o2p. 4pl. July 1909. 40c. 

Report of the State Botanist 1909. ii6p. iopl. May 1910. 45c. 

Archeology. 16 Beauchamp, W. M. Aboriginal Chipped Stone Imple¬ 
ments of New York. 86p. 2 3pl. Oct. 1897. 25c. 


18 


35 Pl- 


22 


32 


25c. 


Polished Stone Articles used by the New York Aborigines. 
Nov. 1897. 25c. 

Earthenware of the New York Aborigines. 78p. 33PI. Oct. 


4 i 


50 

] 

55 

73 


1900. 

2 8pl. 

) - 

Mar. 


i9op. i6pl. 2 maps. 


io4p. 

1898. 

Mar. 


1902 


- Aboriginal Occupation of New York. 

30c. 

- Wampum and Shell Articles used by New York Indians. i66p. 

Mar. 1901. 30c. 

- Horn and Bone Implements of the New York Indians. ii2p. 43pl. 

1902. 30c. 

- Metallic Implements of the New Yorx Indians. 94p. 38pl. June 

25c. 

- Metallic Ornaments of the New Yorx Indians. i22p. 37pl. Dec. 


1903. 30c. 

78 - History of the New York Iroquois. 34op. i7pl. map. Feb. 1905. 

75c, doth. 

87 — Perch Lake Mounds. 84p. iipl. Apr. 1905. Out of print. 

89 - Aboriginal Use of Wood in New York. 190P. 35pl. June 1905. 

35 c - 

108 - Aboriginal Place Names of New York. 336p. May 1907. 40c. 

113 - Civil, Religious and Mourning Councils and Ceremonies of Adop¬ 
tion. n8p. 7pl. June 1907. 25c. 

117 Parker, A. C. An Erie Indian Village and Burial Site. io2p. 38pl. 
Dec. 1907. 30c. 

125 Converse, H. M. & Parker, A. C. Iroquois Myths and Legends. 196P. 
il. npl. Dec. 1908. 50c. 

144 Parker, A. C. Iroquois Uses of Maize and Other Food Plants. i2op. 
3ipl. il. Nov. 1910. 30c. 

Miscellaneous. Ms. 1 (62) Merrill, F. J. H. Directory of Natural History 
Museums in United States and Canada. 236p. Apr. 1903. 30c. 

66 Ellis, Mary. Index to Publications of the New York State Natural 
History Survey and New York State Museum 1837-1902. 4i8p. June 

1903. 75 c < doth. 

Museum memoirs 1889-date. Q. 

1 Beecher, C. E. & Clarke, J. M. Development of Some Silurian Brachi- 

opoda. 96p. 8pl. Oct. 1889. $1. 

2 Hall, James & Clarke, J. M. Paleozoic Reticulate Sponges. 35op. il. 7opl. 

1898. $2, doth. 

3 Clarke, J. M. The Oriskany Fauna of Becraft Mountain, Columbia Co., 

N. Y. i28p. 9pl. Oct. 1900. 80c. 

4 Peck, C. H. N. Y. Edible Fungi, 1895-99. 10 6p. 25pl. Nov. 1900. [$1.25.] 

This includes revised descriptions and illustrations of fungi reported in the 49th, 51st and 
52d reports of the State Botanist. 


























NEW YORK STATE EDUCATION DEPARTMENT 


5 Clarke, J. M. & Ruedemann, Rudolf. Guelph Formation and Fauna of 

New York State. 196P. 2ipl. July 1903. $1.5°. cloth. 

6 Clarke, J. M. Naples Fauna in Western New York. 2 68p. 2 6pl. map. 
$2, cloth. 

7 Ruedemann, Rudolf. Graptolites of New York. Pt 1 Graptolites of the 

Lower Beds. 35op. i7pl. Feb. 1905. $1.50, cloth. 

8 Felt, E. P. Insects Affecting Park and Woodland Trees, v.i. 46op. 

il 1 48pl. Feb. 1906. $2.50, cloth;v.2 548p.il.22pl. Feb. 1907. $2, cloth', 

9 Clarke, J. M. Early Devonic of New York and Eastern North America. 

Pt 1. 366p. il. 7opl. 5 maps. Mar. 1908. $2.50, cloth; Pt 2, 250P. il. 36pl. 

4 maps. Sept. 1909. $2, cloth. 

10 Eastman, C. R. The Devonic Fishes of the New York Formations. 

236P. i5pl. 1907. $1.25, cloth. 

11 "Ruedemann, Rudolf. Graptolites of New York. Pt 2 Graptolites of 

the Higher Beds. 584P. il. 2 tab. 3ipl. Apr. 1908. $2.50, cloth. 

12 Eaton, E. H. Birds of New York. v. 1, 50ip. il. 42pl. Apr. 1910. 
$3, cloth; v. 2, In press. 

13 Whitlock, H. P. Calcitesof New York. 190p.il.27pl. Oct.1910.—, cloth. 
Clarke, J. M. & Ruedemann, Rudolf. The Eurypterida of New York. 
In press. 

Natural history of New York. 30V. il. pi. maps. 4to. Albany 1842-94. 
division 1 zoology. De Kay, James E. Zoology of New York; or, The 
New York Fauna; comprising detailed descriptions of all the animals 
hitherto observed within the State of New York with brief notices of 
those occasionally found near its borders, and accompanied by appropri¬ 
ate illustrations. 5V. il. pi. maps. sq. 4to. Albany 1842-44. Out of print. 
Historical introduction to the series by Gov. W. H. Seward. i78p. 
v. i pt i Mammalia. 131 4 - 46p. 33ph T842. 

300 copies with hand-colored plates. 

v. 2 pt 2 Birds. 12 + 38op. i4Tpl. 1844. 

Colored plates. 

v. 3 pt 3 Reptiles and Amphibia. 7 + 98p. pt 4 Fishes. 15 + 415P. 1842. 

pt 3-4 bound together. 

v. 4 Plates to accompany v. 3. Reptiles and Amphibia. 2301. Fishes. 
79pl. 1842. 

300 copies with hand-colored plates. 

v. 5 pt 5 Mollusca. 4 + 271P. 4opl. pt 6 Crustacea. 7op. 13pi. 1843-44. 
Hand-colored plates; pt 5-6 bound together. 

division 2 botany. Torrey, John. Flora of the State of New Yone; com¬ 
prising full descriptions of all the indigenous and naturalized plants hith¬ 
erto discovered in the State, with remarks on their economical and medical 
properties. 2V. il. pi. sq. 4to. Albany 1843. Out of print. 
v. 1 Flora of the State of New York. 12 + 484P. 72pl. 1843. 

300 copies with hand-colored plates. 

v. 2 Flora of the State of New York. 572p. 89PI. 1843. 

300 copies with hand-colored plates. 

division 3 mineralogy. Beck, Lewis C. Mineralogy of New York; com" 
prising detailed descriptions of the minerals hitherto found in the State 
of New York, and notices of their uses in the arts and agriculture, il. pi. 
sq. 4to. Albany 1842. Out of print. 

v. 1 pt 1 Economical Mineralogy, pt 2 Descriptive Mineralogy. 24 + 536p. 
1842. 

8 plates additional to those printed as part of the text. 

division 4 geology. Mather, W. W.; Emmons, Ebenezer; Vanuxem, Lard- 
ner & Hall, James. Geology of New York. 4V. il. pi. sq. 4to. Albany 
1842-43. Out of print. 

v. 1 pt 1 Mather, W. W. First Geological District. 37 + 653P. 46pl. 1843. 
v. 2 pt 2 Emmons, Ebenezer. Second Geological District. 10 + 43 7p. 
i7pl. 1842. 

v. 3 pt 3 Vanuxem, Lardner. Third Geological District. 3o6p. 1842. 

v. 4 pt 4 Hall, James. Fourth Geological District. 22 + 683P. i9pl. 
L ma P- i8 43 - 


MUSEUM PUBLICATIONS 


division 5 agriculture. Emmons, Ebenezer. Agriculture of New York; 
compnsmg an account of the classification, composition and distribution 
oi the soils and rocks and the natural waters of the different geological 
formations, together with a condensed view of the meteorology and agri¬ 
cultural productions of the State. 5V. il. pi. sq. 4to. Albany 1846—54. 
Out of print. : 0 

v. 1 Soils of the State, their Composition and Distribution. 11 + 5 7ip. 2ipl. 
1846. 

v. 2 Analysis of Soils, Plants, Cereals, etc. 8 4* 343 4- 4&p. 42 pi. 1840. 

With hand-colored plates. 

v. 3 Fruits, etc. 8 4 - 34op. 1851. 

v. 4 Plates to accompany v. 3. 95pl. 1851. 

Hand-colored. 

V. 5 Insects Injurious to Agriculture. 8 + 272P. 5opl. 1854. 

With hand-colored plates. 

division 6 paleontology. Hall, James. Paleontology of New York. 8v. 

il. pi. sq.^to. Albany 1847—94. Bound in cloth. 
v. 1 Organic Remains of the Lower Division of the New York System. 

2 3 + 338P. 99ph 1847. Out of print. 
v. 2 Organic Remains of Lower Middle Division of the New York System. 

8 4 - 362P. io4pl. 1852. Out of print. 
v - 3 Organic Remains of the Lower Helderberg Group -and the Oriskany 
Sandstone, pt 1, text. 12 + 532P. 1859. [$3.50] 

- pt 2. i43pl. _ 1861. [$2.50] 

v. 4 Fossil Brachioppda of the Upper Helderberg, Hamilton, Portage and 
Chemung Groups, n 4 - 1 4 - 428p. 69PI. 1867. $2.50. 

v. 5 pt 1 Lamellibranchiata 1. Monomyaria of the Upper Helderbergs; 
Hamilton and. Chemung Groups. 18 4 - 268p. 45pl. 1884.. $2.50. 

- Lamellibranchiata 2. Dimyaria of the Upper Helderberg, Ham¬ 
ilton, Portage and Chemung Groups. 62 4- 293P. 5ipl. 1885. $2.50. 

-pt 2 Gasteropoda, Petropoda and Cephalopoda of the Upper Helder¬ 
berg, Hamilton, Portage and Chemung Groups. 2V. 1879. v. 1, text. 

15 4 - 492p. v.2, 12opl. $2.50 for 2 v. 

- & Simpson, George B. v. 6 Corals and Bryozoa of the Lower and Up¬ 
per Helderberg and Hamilton Groups. 24 + 298P. 67pl. 1887. $2.50. 

- & Clarke, John M. v. 7 Trilobites and other Crustacea of the Oris¬ 
kany, Upper Helderberg, Hamilton, Portage, Chemung and Catskill 
Groups. 64 4 - 236P. 46pl. 1888. Cont. supplement to v. 5, pt 2. Ptero- 

poda, Cephalopoda and Annelida. 42p. i8pl. 1888. $2.50. 

■- & Clarke, John M. v. 8 pt 1. Introduction to the Study of the Genera 

of the Paleozoic Brachiopoda. 16 4 - 367P. 44pl. 1892. $2.50. 

- & Clarke, John M. v. 8 pt 2 Paleozoic Brachiopoda. 16 4 - 394p. 64pl. 

1894. $2.50. 

Catalogue of the Cabinet of Natural History of the State of New York and 
of the Historical and Antiquarian Collection annexed thereto. 242P. 8vo. • 
1853. 

Handbooks 1893-date. 

In quantities, 1 cent for each 16 pages or less. Single copies postpaid as below. 

New York State Museum. 52p. il. Free. 

Outlines, history and work of the museum with list of staff 1902. 

Paleontology. i2p. Free. 

Brief outline of State Museum work in paleontology under heads: Definition: Relation to 
biology; Relation to stratigraphy; History of paleontology in New York. 

Guide to Excursions in the Fossiliferous Rocks of New York. i2qp. Free. 

Itineraries of 3 2 trips covering nearly the entire series of Paleozoic rocks, prepared specially 
for the use of teachers and students desiring to acquaint themselves more intimately with the 
classic rocks of this State. 

Entomology. i6p. Free. 

Economic Geology. 44p. Free. 

Insecticides and Fungicides. 2op. Free. 

Classification of New York Series of Geologic Formations. 32p. Free. 











NEW YORK STATE EDUCATION DEPARTMENT 


Geologic maps. Merrill, F. J. H. Economic and Geologic Map of the 
State of New York; issued as part of Museum bulletin 15 and 48th Museum 
Report, v. 1. 59 x 67 cm. 1894. Scale 14 miles to 1 inch. 15c. 

-Map of the State of New York Showing the Location of Quarries of 

Stone used for Building and Road Metal. Mus. bul. 17. 1897. Free. 

- Map of the State of New York Showing the Distribution of the Rocks 

Most Useful for Road Metal. Mus. bul. 17. 1897. Free. 

- Geologic Map of New York. 1901. Scale 5 miles to 1 inch. In atlas 

form $3 ; mounted on rollers $5. Lower Hudson sheet 60c. 

The lower Hudson sheet, geologically colored, comprises Rockland, Orange, Dutchess, 
Putnam, Westchester, New York, Richmond, Kings, Queens and Nassau counties, and parts 
of Sullivan, Ulster and Suffolk counties; also northeastern New Jersey and part of western 
Connecticut. 

- Map of New York Showing the Surface Configuration and Water Sheds. 

1901. Scale 12 miles to 1 inch. 15c. 

- Map of the State of New York Showing the Location of its Economic 

Deposits. 1904. Scale 12 miles to 1 inch. 15c. 

Geologic maps on the United States Geological Survey topographic base. 
Scale 1 in. = 1 m. Those marked with an asterisk have also been pub¬ 
lished separately. 

*Albany county. Mus. rep’t 49, v. 2. 1898. Out of print. 

Area around Lake Placid. Mus. bul. 21. 1898. 

Vicinity of Frankfort Hill [parts of Herkimer and Oneida counties], Mus. 
rep’t 5T, v. 1. 1899. 

Rockland county. State geol. rep’t 18. 1899. 

Amsterdam quadrangle. Mus. bul. 34. 1900. 

* Parts of Albany and Rensselaer counties. Mus. bul. 42. 1901. Free. 

♦Niagara river. Mus. bul. 45. 1901. 25c. 

Part of Clinton county. State geol. rep’t 19. 1901. 

Oyster Bay and Hempstead quadrangles on Long Island. Mus. bul. 48. 
1901. 

Portions of Clinton and Essex counties. Mus. bul. 52. 1902. 

Part of town of Northumberland, Saratoga co. State geol. rep’t 21. 1903, 

Union Springs, Cayuga county and vicinity. Mus. bul. 69. 1903. 

*01ean quadrangle. Mus. bul. 69. 1903. Free. 

♦Becrait Mt with 2 sheets of sections. (Scale 1 in. = \ m.) Mus. bul. 69 
1903. 20c. 

♦Canandaigua-Naples quadrangles. Mus. bul. 63. 1904. 20c. 

♦Little Falls quadrangle. Mus. bul. 77. 1905. Free. 

♦Watkins-Elmira quadrangles. Mus. bul. 81. 1905. 20c. 

♦Tully quadrangle. Mus. bul. 82. 1905. Free. 

♦Salamanca quadrangle. Mus. bul. 80. 1905. Free. 

♦Mooers quadrangle. Mus. bul. 83. 1905. Free. 

♦Buffalo quadrangle. Mus. bul. 99. 1906. Free. 

♦Penn Yan-Hammondsport quadrangles. Mus.’bul. 101. 1906. 20c. 

♦Rochester and Ontario Beach quadrangles. Mus. bul. 114. 20c. 

*Long Lake quadrangle. Mus. bul. 115. Free. 

♦Nunda-Portage quadrangles. Mus. bul. 118. 20c. 

♦Remsen quadrangle. Mus. bul. 126. 1908. Free. 

♦Geneva-0 vid quadrangles. Mus. bul. 128. 1909. 20c. 

♦Port Leyden quadrangle. Mus. bul. 135. 1910. Free. 

*Auburn-Genoa quadrangles. Mus. bul. 137. 1910. 20c. 

* Elizabethtown and Port Henry quadrangles. Mus. bul. 138. 1910. 15c. 

♦Alexandria Bay quadrangle. Mus. bul. 145. Free. 

♦Cape Vincent quadrangle. Mus. bul. 145'. Free. 

♦Clayton quadrangle. Mus. bul. 145. Free. 

♦Grindstone quadrangle. Mus. bul. 145. . Free. 

♦Theresa quadrangle. Mus. bul. 145. Free. 



























































































































































EDUCATION DEPARTMENT 

JOHN M. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 
STATE MUSEUM 


BULLETIN 145 

ALEXANDRIA BAY QUADRANGLE 



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fell Wyanoke l. y. / 


larrow I 


til 


Scow I 


Rabbit I 


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Pi lot I. 

^.Willoughby! 


9 / ■■ 


Mink I. 


Third Brother! 


j* St Margarettes 
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Hemlock I. 


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feJSwyi 


Deerf. 'Resort 1. 


icy land 1 


iteamboaT I 


\mmm 

Br/'tAY/tTf j?/j>2yr-1 


arboi 


■£/v noc/f <?/ 


mrniW-a 

jlF'GVJV ./V^f L d 


R&S 3 s! 3 &$ra 


MM 


(The-re-Sds) 


76 ° 00 ' 


55 


75 ” 45 ' 


r A X A 1 ) A 


i 0 iis^ 

/ Lb ■, / ^ J x 

Round 1. / 

liml ’ Ironsides l^s^ >' Lif*\ 

. Y* \ gt 


S i,r° undl 

v/ 


7 <?• Shanteel. 

b w**3M mm ifjiwK 

OENADlCR l.L.H. C 1 ’’^ ' \- ^ 4 

Little Grenad^K^o ’ WhiS ^ L V Spare 1^ ’ b/fLV^. ’ 

^ . V / aN * > ^ 

£p°rt l , \\ 

-»* ' »' k X 

Douglas 4 4' 




Bluff l/ , /SSummerlandc? 

Sldfewildi- ^ T C/ 

' • . \o < • 


. 0 e\^ v 


20 ' 


• , JHBHHiHSi ®| 0 - _ ^Bi rciii". .-' , 

7- _ t /<f >( > '• <7 

. ^Lotus/f. V/ Schooner ,7 


5C5 


125 ' 


/ 
i/4 


76“oo' 


55' 


LEGEND 

Sedimentary Rocks 




Glacial deposits, conceal¬ 
ing boundaries. 

J 


Theresa formation 
Sandy, magnesian lime¬ 
stone, with beds of weak 
sandstone. 


Potsdam sandstone. Red, 
white and buff sandstone 
with sonte coarse con¬ 
glomerate. 


Grenville limestone. Gen¬ 
erally coarse, white crys¬ 
talline limestone. 


Grenville quartzite. 
Coarse and fine, pure and 
impure quartzites and 
quartz schists. 


Grenville schists. Com¬ 
prising amphibolites and 
all other Grenville rocks 
except quartzites and 
limestones. 


GS 


G! 


Grenville rocks, cut by 
numerous dikes from the 
igneous rocks. 


Igneous Rocks 


^/1 


Diabase dikes, of late Pre¬ 
cambric age. 


\,qyj 

KLsV-Li 


Various igneous rocks 
holding frequent inclu¬ 
sions of the Grenville 
rocks. 




L-Y-. -/T- 


Alexandria syenite, Pic- 
ton granite, of early Pre¬ 
cambric age but younger 
than the Laurentian. 


Laurentian granite-gneiss. 



Scale e25oo 


2 


3 


4 * 


4 Miles 


Geology By H. P. Cushing, 
1907-08. 

Wells Island by C. H. Smyth, Jr., 
1908. 


o 


Oontovn.’ interval 2 0 ft-et . 
Datum is inesut seu level. 


5 I&iameters 


PRECAMBRIC PRECAMBRIC UPPER CAMBRIC PLEISTOCENE 






















































































































































































































































EDUCATION DEPARTMENT 

JOHN M. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 
STATE MUSEUM 


BULLETIN 145 
CLAYTON QUADRANGLE 



/Calumet" II 


Whisky 


Washington 

<' iLVYTt 


Arabella I, 


?7\L 


--. 




- 


JpOlm urnoui,"- 


Independence 


Point. 


76'15 


76’0C 


44 


H fpkory J, ' | / 


. R !S H £L 


'£u 


Little Galumet I. , 


■AMD 


° mtar , 




to 


ket l\ 


H 




246 


Sawmill 


Hay 


246 


Pt.Salubrious 


lines Point 


L JJ 




(Sax- ke tts Harbor) 


76 V? 


Scale esfoo 


4 Miles 


Geology by H. P. Cushing (northeast half) ar 
R. Ruedemann (southwest half), 
1908. 


APPROXIMATE MEAN 
DECLINATION 1902 


(ioiitoar intei'^aJT O foot . 
Ucctucm is mean sea, level,* 


LEGEND 

Sedimentary Rocks 


Pleistocene deposits con¬ 
cealing other formations. 


St 


Trenton limestone. Black 
and gray, mostly thin- 
bedded limestone. 


Sbr 


Watertown and Leray 
limestones. Massive, 
black limestone, cherty in 
the lower (Leray) mem¬ 
ber. 



> 


Lowville limestone. Dove 
and blue dove limestone, 
both thick and thin- 
bedded. 



Pamelia limestone. Black 
and dove limestones, alter¬ 
nating with gray and 
white earthy limestones. 


y 

A 

Theresa and Tribes Hill 
formations. Sandy, cal¬ 
careous dolomites, with 
some beds of coarse, weak 
sandstone. 

r—- > 

€p 

Potsdam sandstone. Red, 
white and buff sandstone 
with some coarse con¬ 
glomerate. 

J 



I- , feM 
Vg-C |.pgn; 

Igneous rocks holding in¬ 
clusions of the Grenville 
rocks. 


Picton granite, of early 1 
Precambric age, b u t ( 
yoimger than the Lauren- 
tian. 


-Lgh 


Laurentian granite-gneiss; 
exposed only in small out¬ 
line by river east of Clay¬ 
ton. 

J 



Fault Lines 


PRECAMBRIC UPPER CAMBRIC LOWER SILURIC PLEISTOCENE 
















































































































































EDUCATION DEPARTMENT 

JOHN NT. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE (. 

STATE MUSETJJ 


NEW YORK 


BULLETIN 145 

GRINDSTONE QUADRANGLE 



Hog I 
Reed I. 


Smoke t 


0 ^ 

^GANANOQUE NARROWS 


• JACKS TRA W L.H. 


X> 

5 '-:,n.V. 


EC 

Bucksl. ' 


Marvin I. 


LUrWiylslfc! 


Robbins I 


'ackenham 


r IV- 

^Beckwith I 
Gol borne L 


Black Ant I 


I'leoiLte] 


Calumet 


I CJftytorv) 




7615 ' 


76 'oo; 

—nA 4 


Ul 


1 


Scale ezioo 

•J. ^ O 1 _ 3 _ _ _ :> _ _ _ 4 Miles 


Geology by H. P. Cushing and C. H. Smyth, Jr. 
1908. 


LEGEND 


Sedimentary Rocks 




LlI 


* » .«v 


Glacial deposits as over¬ 
print, where underlying 
rock is widely concealed. 

J 


UJ 

O 

c/> 

Ld 



-\ 


Theresa formation. 
Sandy, blue gray, 
dolomite, weathering to 
rotten stone, with some 
interbedded weak sand¬ 
stone. 


O 

oc 

CQ 


>0 


•Gp 

Potsdam sandstone. Red, 
white and buff quartz 
sandstone, with some 
coarse conglomerate. 

J 


oc 

t±j 

CL 

CL 

D 


__ T 

Gs 


Grenville schists. Variable 
rocks, comprising all 
Grenville rocks, except 
quartzite and limestone. 



Grenville quartzite. 
Coarse and fine, pure and 
impure quartzites and 
quartz schists. 


O 

DC 

CQ 

r< 

o 

Ld 

DC 

CL 



Grenville rocks cut by 
numerous dikes of the 
igneous rocks. 


Igneous Rocks 



Diabase dikes. 





Igneous rocks containing 
inclusions of the Grenville 
rocks. 


O 

DC 

CQ 





o 

Ijj 

DC 

Q. 


Pieton granite. Coarse 
red granite with fine¬ 
grained phases; younger 
than the Laurentian. 



Laurentian granite-gneiss^ 


5 ivilumetei-w 




k 


1 


o 


( 'ontoxiT* intei^vnl 2 O feet. 
Datum is mean sea. level .. 































































































































































































































EDUCATION DEPARTMENT 

JOHN Tvt. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 

STATE MUSEUM 


BULLETIN 145 PLATE 43 






















































































































































































EDUCATION DEPARTMENT 

JOHN TvT. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 
STATE MUSEUM 


BULLETIN 145 

CAPE VINCENT QUADRANGLE 





Milton Id. 

T 


Halliday Pt. 

WmwM 


BROWN PT. i 




7 Stony Island.) 


LEGEND 



Trenton limestone. Black 
and gray, mostly thin- 
bedded limestone. 


__J 

Watertown and Leray L 
limestones. Massive,] 
black limestone, cherty in 
the lower (Leray) mem¬ 
ber. 



Dove 

and blue dove limestone, 
both thick and thin- 
bedded. . 


S 


Sea] e 62,500 

12 3 

_i_i_X—_l— 

Contour Interval 20 feet 
Datumis mean Sea level 


4 MiJes 


Geology by R. Ruedemann 
1908. 


LOWER SILURIC 




















































































































(Alexandria B t-qy) 




me Mills 




®$ssshS$ 






Black 


r i Xi i’hi}* 

lu^wrrvnlle 


EDUCATION DEPARTMENT 

JOHN N£. CLARKE 
STATE GEOLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 
STATE MUSEUM 


BULLETIN 145 
THERESA QUADRANGLE 


Scale 62500 
1 2 


4 Miles 


5 JGlcxmetea^s 


Contour irrtei’val 20feet. 

DcUum, is mean sea 1e\'e7. 


A '*** a 
7evel■ 


Sbr 


— 'H . ~ . ‘It ' d< .... „ 


Vertical Scale twice the horizontal 


7L'oO' 

4 4 *v 


75’ 45’ 

mz=tjg&m 4 $ 


Go, 


. : 'K 4 ' 

■■-a 00 

75 ° 4 -£>' 


I Wat&rtcrwn,; 


(eology by H. P. Cushing, 
1906-07. 


LEGEND 

Sedimentary Rocks 




Pleistocene deposits. As 
overprint on other rocks 
where’ boundaries are 
concealed, and mapping 
uncertain. 


Trenton limestone. Gray 
and black, mostly thin- 
bedded limestones. 


Sbr 


Leray and Watertown 
limestones Massive, 
black limestone, often 
cherty. 


Lowville limestone. Dove 
and blue limestone. 


Pamelia limestone. Gray 
and white, impure mag¬ 
nesian limestone, alter¬ 
nating with blue and dove 
limestone. 


Theresa and Tribes Hill 
formations. Sandy, cal¬ 
careous dolomites, alter¬ 
nating with coarse, weak 
sandstone teds. 


Potsdam sandstone. 
White, yellow, gray, red 
and black sandstone, 
with local conglomerate./ 


Grenville limestone.. 
White crystalline lime¬ 
stone, with a local, bluish, 
less crystalline phase. 


kBHnl 


Grenville quartzite. 
Coarse and fine, pure and 
impure, quartzites and 
quartz schists. 


Grenville rocks other than 
limestone and quartzite; 
various schists with thin 
limestone bands. 


Grenville rocks cut to 
pieces by dikes from the 
granite-gneiss. 

Igneous Rocks 




:V- 






Theresa syenite. Early 
Precambric but younger 
than the granite-gneiss. 


Laurentian granite-gneiss 
holding numerous inclu¬ 
sions of the Grenville 
rocks. 


LgV~ ■ 


Laurentian granite-gneiss. 


























































































































































































































